Display apparatus

ABSTRACT

A semi-spherical system holding mechanism 8 such as to cover the head portion of the user is provided in the upper portion of a user holding mechanism 9 such as chair, sofa, or the like. A display apparatus 7 is fixed in the system holding mechanism 8. In the display apparatus 7, a video image displayed on a display panel 14 is enlarged by a lens 13, so that a virtual image is formed. The virtual images which are observed by the right and left eyes of the user are arranged at the same position in a space.

TECHNICAL FIELD

The invention relates to a display apparatus and, more particularly, toa display apparatus for enabling the user to appreciate, for example, avirtual image with presence in a relaxed state.

BACKGROUND ART

Hitherto, as a display apparatus which can provide a large video imagefor allowing the user to feel presence, for example, there are a videoprojector, an HMD (Head Mount Display), and the like.

However, as shown in FIG. 145, since the video projector opticallyenlarges a video image and displays it on a screen, not only the videoprojector but also the screen is necessary to appreciate the videoimage. In this case, to display a large video image onto the screen, acertain distance is needed between the video projector and the screen.Therefore, if a room is narrow, it is difficult to display a large videoimage.

On the other hand, an HMD or HUD (Head Up Display) such that a videoimage to be displayed by a liquid crystal display or the like isenlarged by an optical system such as a lens or the like and a virtualimage is formed and this virtual image is provided to the user has beenput into practical use in recent years.

In a case where an object exists at a position near the lens than afocal distance, a virtual image is formed on the object side. Thedetails of its forming principle have been disclosed in, for example,Toshifu Ogura, “The Introduction of Science of Lens (the first volume)”,Asahi Sonorama Co., Ltd., Kazumi Murata, “Optics”, Science Co., Ltd., orthe like.

For example, as shown in FIG. 146, the HMD is constructed by including alens for enlarging a video image and forming a virtual image and adisplay panel (for instance, liquid crystal display or the like)arranged at a position that is closer than a focal distance of the lens.The user attaches the HMD to a head portion and watches the video imagedisplayed on the display panel through a lens, so that he can appreciateits virtual image. That is, the user can appreciate the large virtualimage even if there is no wide space as in case of the video projector.

As shown in FIG. 147, since a width between human eyes (distance betweenthe right and left eyes) is equal to about 56 to 75 mm, as a lens of theHMD, a small lens can be used so long as it can cover such a range. Itis known that it is sufficient that the distance from the rotationalcenter of the eyeball to the lens surface is equal to about 35 mm as anaverage in case of a person with glasses. Therefore, it is possible toconstruct such that when the HMD is attached to the head portion of theuser, the lens is located near the user.

From the above explanation, the HMD can be constructed in a small sizeand, further, the virtual image is appreciated by using it, so that alarge space is not necessary.

A principle such that it is sufficient that the distance from therotational center of the eyeball to the lens surface is equal to about35 mm as an average has been disclosed in, for instance, “GlassesOptics”, Kyoritsu Publishing Co., Ltd., page 101, or the like (in thisliterature, it is assumed that a thickness of glasses lens is equal to 8mm).

However, since the HMD is attached to the head portion and is used,there is a problem that the user feels its attaching sense and a weight.

Although there is a method of using the HMD without attaching it to thehead portion, since a condition that the HMD is attached to the headportion and is used is set as a prerequisite, for the purpose ofrealization of a light weight or the like, a lens diameter is generallyset to the necessary minimum size. In the case of using the HMD withoutattaching to the head portion, accordingly, as shown in FIG. 148, theeyeball is not always located at the front surface (near an opticalaxis) of the lens and, in many cases, a part of the virtual image ismissing and cannot be seen.

Further, the HMD is usually designed so that when it is attached to thehead portion, a pupil is located on the optical axis of the lens. Ashape of lens is also designed so that when the pupil is located on theoptical axis of the lens, aberration becomes the minimum as shown inFIG. 149A. Therefore, in a state where the HMD is used without attachingto the head portion and the pupil is not located on the optical axis ofthe lens as shown in FIG. 149B, the aberration increases, so that it isdifficult to see a clear video image (virtual image).

On the other hand, for example, as shown in FIG. 150, since the HUD isset at a position that is slightly away from the user, a situation thatthe user feels an attaching sense or a weight as in case of the HMD doesnot occur.

In the HUD of FIG. 150, the video image displayed on the display panelis enlarged through a lens, the enlarged image is reflected by a halfmirror, and the user looks at its reflected light, so that a virtualimage is formed. Since the half mirror can transmit the external light,the user can also see an ambient background (situation) as light fromthe outside which transmits the half mirror together with the virtualimage.

The HUD is not used to monitor the video image but is used to observenecessary information while performing some works such as driving of anautomobile, control of an airplane, or the like. As mentioned above,therefore, the HUD has been designed so that the user can see an ambientsituation, thereby enabling the user to confirm information by a virtualimage while concentrating to the work so as not to cause a trouble inthe work.

An angle of visibility of a virtual image which is formed by the HUD isset to a narrow angle shown in, for example, FIG. 150 so that theambient situation can be clearly confirmed.

Therefore, in a case where a video image is appreciated by the HUD, thevideo image is very hard to see and is lacking in power.

Further, in the HUD, since the position of the virtual image from theuser is fixed to about tens of meters ahead in case of the HUD for anautomobile, the infinite point in case of the HUD for an airplane, orthe like, the virtual image cannot be formed at a desired position ofthe user.

Since the user hardly moves the head portion during the operation of theautomobile or the control of the airplane, in the HUD, the virtual imageis formed so that it can be seen only from a predetermined position. Itis, consequently, difficult for the user to see the virtual image in arelaxed state while moving the head portion to a certain extent.

Moreover, the HUD is designed such that it is installed at a positionthat is slightly away from the user (for example, an upper portion of apanel of an automobile, airplane, or the like) so as not to become anobstacle of the work such as operation of the automobile, control of theairplane, or the like as a prerequisite. That is, in order to performsome work by the human being, at least a space where an arm can enter isnecessary and the HUD is installed so that such a space can be assured.Therefore, at least the space where the arm can enter is needed betweenthe HUD and the user.

For example, a fact that a front forearm (distance from an arm chin rearedge to a finger tip point when an upper arm is naturally droppeddownward and a palm is directed to the inside and the forearm ishorizontally bent ahead) of an adult man is equal to 45.1 cm has beendisclosed in Jiro Ohara, Ken Uchida, Yoshiyuki Ueno, and KazutoshiUchida, “The Human Body is Measured”, Nihon shuppan Service Co., Ltd.According to this literature, a wider space is needed between the HUDand the user.

Besides the foregoing HMD and HUD, the virtual image can be alsoobserved by, for example, a view finder or the like of a video camera asshown in FIG. 151. In this case, however, it is necessary to grasp thevideo camera with the hand or the like and this causes the user to feela troublesomeness. Even if the video camera is fixed by a tripod or thelike, in the viewfinder, since the virtual image can be seen by only oneeye, it is hard to obtain a video image with presence.

The invention is made in consideration of such a situation and enablesthe user to appreciate a virtual image with presence in a relaxed state.

DISCLOSURE OF INVENTION

A display apparatus according to claim 1 is characterized in that avideo image providing apparatus comprises: display means for displayinga video image and an enlargement optical system for forming a virtualimage by enlarging the video image displayed on the display means andfor arranging the virtual image which is observed by the left and righteyes of the user at a same position on a space, and that the displayapparatus further has fixing means for fixing the video image providingapparatus to a predetermined object other than the user.

A display apparatus according to claim 42 is characterized in that amonga plurality of lenses constructing an enlargement optical system forforming a virtual image by enlarging a video image displayed on displaymeans for displaying the video image, a refractive power of the lensarranged at a position that is the closest to the display means islarger than those of the other lenses and a refractive power of the lensarranged at a position that is the farthest from the display means issmaller than those of the other lenses.

In the display apparatus according to claim 1, the fixing means fixesthe video image providing apparatus to a predetermined object other thanthe user.

In the display apparatus according to claim 42, among a plurality oflenses constructing the enlargement optical system, the refractive powerof the lens arranged at the position that is the closest to the displaymeans is larger than those of the other lenses and the refractive powerof the lens arranged at the position that is the farthest from thedisplay means is smaller than those of the other lenses.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a construction of the first embodimentof a virtual image providing system to which the invention is applied;

FIG. 2 is a cross sectional view of a top view showing a firstconstructional example of a display apparatus 7;

FIG. 3A is a perspective view showing a constructional example of lenses13L and 13R in FIG. 2;

FIG. 3B is a diagram for explaining a horizontal angle of visibility ofa virtual image viewed via the lens holder of FIG. 3A;

FIGS. 4A and 4B are diagrams for explaining a horizontal angle ofvisibility and a vertical angle of visibility respectively, of a virtualimage;

FIGS. 5A and 5B are cross sectional views showing a constructionalexample of the lenses 13L and 13R in FIG. 2 where the pupil is, and isnot, located on the optical axis, respectively;

FIG. 6 is a perspective view showing a constructional example of a selflight emitting type device;

FIG. 7 is a perspective view showing a constructional example of atransmission light control type device;

FIG. 8 is a cross sectional view showing a constructional example of areflection light control device;

FIG. 9 is a cross sectional view of a left side diagram showing a secondconstructional example of the display apparatus 7;

FIGS. 10A and 10B are front view and cross sectional views,respectively, showing a third constructional example of the displayapparatus 7;

FIG. 11 is a cross sectional view of a top view showing the fourthconstructional example of the display apparatus 7;

FIGS. 12A and 12B are cross sectional views of a top view, respectively,and a left side view showing the fifth constructional example of thedisplay apparatus 7;

FIG. 13 is a cross sectional view of a left side view showing the sixthconstructional example of the display apparatus 7;

FIG. 14 is a diagram for explaining a function of a cylindrical lens 41in FIG. 13;

FIG. 15 is a cross sectional view of a top view showing the seventhconstructional example of the display apparatus 7;

FIGS. 16A and 16B are cross sectional views of a top view and a leftside view, respectively, showing the eighth constructional example ofthe display apparatus 7;

FIG. 17 is a block diagram showing a construction of the secondembodiment of a virtual image providing system (stereoscopic imagedisplay system) to which the invention is applied;

FIG. 18 is a diagram showing a system for displaying a stereoscopicvideo image by a projector;

FIG. 19 is a block diagram showing a constructional example of the thirdembodiment of a virtual image providing system to which the invention isapplied;

FIG. 20 is a perspective view showing a constructional example of an armstand 81 in FIG. 19;

FIGS. 21A and 21B are diagrams depicting various methods of detachablyaffixing the display apparatus 7;

FIG. 22 is a diagram showing a constructional example of the firstembodiment of an ocular lens constructing an enlargement optical system;

FIG. 23 is a diagram showing an intermediate region between the centerand the edge of a virtual image;

FIG. 24 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 22;

FIGS. 25A to 25E are diagrams showing the lateral aberrations of theocular lens in FIG. 22;

FIG. 26 is an optical path diagram showing an optical path in the casewhere a pupil position is deviated in FIG. 22;

FIGS. 27A to 27E are diagrams showing lateral aberrations of the ocularlens in FIG. 22 in the case where the pupil position is deviated;

FIG. 28 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 22;

FIGS. 29A to 29E are diagrams showing lateral aberrations of the ocularlens in FIG. 22;

FIGS. 30A to 30E are diagrams showing lateral aberrations of the ocularlens in FIG. 22 in the case where the pupil position is deviated;

FIG. 31 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 22;

FIGS. 32A to 32E are diagrams showing lateral aberrations of the ocularlens in FIG. 22;

FIGS. 33A to 33E are diagrams showing lateral aberrations of the ocularlens in FIG. 22 in the case where the pupil position is deviated;

FIG. 34 is a diagram showing a constructional example of the secondembodiment of an ocular lens constructing an enlargement optical system;

FIG. 35 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 34;

FIGS. 36A to 36E are diagrams showing lateral aberrations of the ocularlens in FIG. 34;

FIG. 37 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 34;

FIGS. 38A to 38E are diagrams showing lateral aberrations of the ocularlens in FIG. 34 in the case where the pupil position is deviated;

FIG. 39 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 34;

FIGS. 40A to 40E are diagrams showing lateral aberrations of the ocularlens in FIG. 34;

FIGS. 41A to 41E are diagrams showing lateral aberrations of the ocularlens in FIG. 34 in the case where the pupil position is deviated;

FIG. 42 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 34;

FIGS. 43A to 43E are diagrams showing lateral aberrations of the ocularlens in FIG. 34;

FIGS. 44A to 44E are diagrams showing lateral aberrations of the ocularlens in FIG. 34 in the case where the pupil position is deviated;

FIG. 45 is a diagram showing a constructional example of the thirdembodiment of an ocular lens constructing an enlargement optical system;

FIG. 46 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 45;

FIGS. 47A to 47E are diagrams showing lateral aberrations of the ocularlens in FIG. 45;

FIG. 48 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 45;

FIGS. 49A to 49E are diagrams showing lateral aberrations of the ocularlens in FIG. 45 in the case where the pupil position is deviated;

FIG. 50 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 45;

FIGS. 51A to 51E are diagrams showing lateral aberrations of the ocularlens in FIG. 45;

FIGS. 52A to 52E are diagrams showing lateral aberrations of the ocularlens in FIG. 45 in the case where the pupil position is deviated;

FIG. 53 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 45;

FIGS. 54A to 54E are diagrams showing lateral aberrations of the ocularlens in FIG. 45;

FIGS. 55A to 55E are diagrams showing lateral aberrations of the ocularlens in FIG. 45 in the case where the pupil position is deviated;

FIG. 56 is a diagram showing a constructional example of the fourthembodiment of an ocular lens constructing an enlargement optical system;

FIG. 57 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 56;

FIGS. 58A to 58E are diagrams showing lateral aberrations of the ocularlens in FIG. 56;

FIG. 59 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 56;

FIGS. 60A to 60E are diagrams showing lateral aberrations of the ocularlens in FIG. 56 in the case where the pupil position is deviated;

FIG. 61 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 56;

FIGS. 62A to 62E are diagrams showing lateral aberrations of the ocularlens in FIG. 56;

FIGS. 63A to 63E are diagrams showing lateral aberrations of the ocularlens in FIG. 56 in the case where the pupil position is deviated;

FIG. 64 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 56;

FIGS. 65A to 65E are diagrams showing lateral aberrations of the ocularlens in FIG. 56;

FIGS. 66A to 66E are diagrams showing lateral aberrations of the ocularlens in FIG. 56 in the case where the pupil position is deviated;

FIG. 67 is a diagram showing a ninth constructional example of thedisplay apparatus 7;

FIG. 68 is a diagram showing a tenth constructional example of thedisplay apparatus 7;

FIG. 69 is a diagram showing a 11th constructional example of thedisplay apparatus 7;

FIG. 70 is a diagram showing a 12th constructional example of thedisplay apparatus 7;

FIG. 71 is a diagram showing a 13th constructional example of thedisplay apparatus 7;

FIG. 72 is a diagram showing a 14th constructional example of thedisplay apparatus 7;

FIG. 73 is a diagram showing a 15th constructional example of thedisplay apparatus 7;

FIG. 74 is a diagram showing a 16th constructional example of thedisplay apparatus 7;

FIG. 75 is a diagram showing a 17th constructional example of thedisplay apparatus 7;

FIG. 76 is a diagram showing a 18th constructional example of thedisplay apparatus 7;

FIG. 77 is a diagram showing a 19th constructional example of thedisplay apparatus 7;

FIG. 78 is a diagram showing a constructional example of the fifthembodiment constructing an enlargement optical system;

FIG. 79 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of an ocularlens in FIG. 78;

FIGS. 80A to 80E are diagrams showing lateral aberrations of the ocularlens in FIG. 78;

FIG. 81 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 78;

FIGS. 82A to 82E are diagrams showing lateral aberrations of the ocularlens in FIG. 78 in the case where the pupil position is deviated;

FIG. 83 is a diagram showing a constructional example in whichparameters of the ocular lens in the fifth embodiment are changed;

FIG. 84 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 83;

FIGS. 85A to 85E are diagrams showing lateral aberrations of the ocularlens in FIG. 83;

FIG. 86 is an optical path diagram showing an optical path in the casewhere a pupil position is deviated in FIG. 83;

FIGS. 87A to 87E are diagrams showing lateral aberrations of the ocularlens in FIG. 83 in the case where the pupil position is deviated;

FIG. 88 is a diagram showing another constructional example in whichparameters of the ocular lens in the fifth embodiment are changed;

FIG. 89 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 88;

FIGS. 90A to 90E are diagrams showing lateral aberrations of the ocularlens in FIG. 88;

FIG. 91 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 88;

FIGS. 92A to 92E are diagrams showing lateral aberrations of the ocularlens in FIG. 88 in the case where the pupil position is deviated;

FIG. 93 is a diagram showing a constructional example of the sixthembodiment constructing an enlargement optical system;

FIG. 94 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of an ocularlens in FIG. 93;

FIGS. 95A to 95E are diagrams showing lateral aberrations of the ocularlens in FIG. 93;

FIG. 96 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 93;

FIGS. 97A to 97E are diagrams showing lateral aberrations of the ocularlens in FIG. 93 in the case where the pupil position is deviated;

FIG. 98 is a diagram showing a constructional example in whichparameters of the ocular lens in the sixth embodiment are changed;

FIG. 99 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 98;

FIGS. 100A to 100E are diagrams showing lateral aberrations of theocular lens in FIG. 98;

FIG. 101 is an optical path diagram showing an optical path in the casewhere a pupil position is deviated in FIG. 98;

FIGS. 102A to 102E are diagrams showing lateral aberrations of theocular lens in FIG. 98 in the case where the pupil position is deviated;

FIG. 103 is a diagram showing another constructional example in whichparameters of the ocular lens in the sixth embodiment are changed;

FIG. 104 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 103;

FIGS. 105A to 105E are diagrams showing lateral aberrations of theocular lens in FIG. 103;

FIG. 106 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 103;

FIGS. 107A to 107E are diagrams showing lateral aberrations of theocular lens in FIG. 103 in the case where the pupil position isdeviated;

FIG. 108 is a diagram showing a construction of the seventh embodimentconstructing an enlargement optical system;

FIG. 109 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of an ocularlens in FIG. 108;

FIGS. 110A to 110E are diagrams showing lateral aberrations of theocular lens in FIG. 108;

FIG. 111 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 108;

FIGS. 112A to 112E are diagrams showing lateral aberrations of theocular lens in FIG. 108 in the case where the pupil position isdeviated;

FIG. 113 is a diagram showing a constructional example in whichparameters of the ocular lens in the seventh embodiment are changed;

FIG. 114 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 113;

FIGS. 115A to 115E are diagrams showing lateral aberrations of theocular lens in FIG. 113;

FIG. 116 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 113;

FIGS. 117A to 117E are diagrams showing lateral aberrations of theocular lens in FIG. 113 in the case where the pupil position isdeviated;

FIG. 118 is a diagram showing another constructional example in whichparameters of the ocular lens in the seventh embodiment are changed;

FIG. 119 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 118;

FIGS. 120A to 120E are diagrams showing lateral aberrations of theocular lens in FIG. 118;

FIG. 121 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 118;

FIGS. 122A to 122E are diagrams showing lateral aberrations of theocular lens in FIG. 118 in the case where the pupil position isdeviated;

FIG. 123 is a diagram showing a construction of the eighth embodimentconstructing an enlargement optical system;

FIG. 124 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 118;

FIGS. 125A to 125E are diagrams showing lateral aberrations of theocular lens in FIG. 118;

FIG. 126 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 118;

FIGS. 127A to 127E are diagrams showing lateral aberrations of theocular lens in FIG. 118 in the case where the pupil position isdeviated;

FIG. 128 is a diagram showing a constructional example in whichparameters of the ocular lens in the eighth embodiment are changed;

FIG. 129 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 128;

FIGS. 130A to 130E are diagrams showing lateral aberrations of theocular lens in FIG. 128;

FIG. 131 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 128;

FIGS. 132A to 132E are diagrams showing lateral aberrations of theocular lens in FIG. 128 in the case where the pupil position isdeviated;

FIG. 133 is a diagram showing another constructional example in whichparameters of the ocular lens in the eighth embodiment are changed;

FIG. 134 is a diagram showing a spherical aberration (chromaticaberration), an astigmatism, and a distortion aberration of the ocularlens in FIG. 133;

FIGS. 135A to 135E are diagrams showing lateral aberrations of theocular lens in FIG. 133;

FIG. 136 is an optical path diagram showing an optical path in the casewhere the pupil position is deviated in FIG. 133;

FIGS. 137A to 137E are diagrams showing lateral aberrations of theocular lens in FIG. 133 in the case where the pupil position isdeviated;

FIG. 138 is a diagram showing a 20th constructional example of thedisplay apparatus 7;

FIG. 139 is a diagram showing a 21st constructional example of thedisplay apparatus 7;

FIG. 140 is a diagram showing a 22nd constructional example of thedisplay apparatus 7;

FIG. 141 is a diagram showing a 23rd constructional example of thedisplay apparatus 7;

FIG. 142 is a diagram showing a 24th constructional example of thedisplay apparatus 7;

FIG. 143 is a diagram showing a 25th constructional example of thedisplay apparatus 7;

FIG. 144 is a diagram showing a 26th constructional example of thedisplay apparatus 7;

FIG. 145 is a perspective view showing a construction of an example of aprojector system for displaying an enlarged video image by a projector;

FIG. 146 is a diagram showing a construction of an example of an HMDsystem;

FIG. 147 is a diagram for explaining an eye width of a human being and adistance necessary between a lens and an eyeball;

FIG. 148 is a diagram for explaining a case where a part of a virtualimage is missing and cannot be seen;

FIGS. 149A and 149B are diagrams depicting the lens of an HMD with thepupil located on the optical axis of the lens, and not located on theoptical axis of the lens, respectively;

FIG. 150 is a diagram showing a construction of an example of an HUDsystem; and

FIG. 151 is a diagram showing a construction of an example of a videocamera.

FIG. 152 is a list matching the elements to respective referencenumerals.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows a construction of the first embodiment of a virtual imageproviding system (system denotes a set in which a plurality ofapparatuses are logically collected and it does not care whether theapparatuses in each construction exist in the same casing or not) towhich the invention is applied. In the virtual image providing system,the user can appreciate a virtual image with presence in a relaxedstate.

That is, a user holding mechanism 9 is, for example, a chair, sofa, orthe like to hold the user in a seating state. The user sits down on it,so that he is held in a relaxed state.

A reclining angle adjusting mechanism 27 is provided in a connectingportion of a reclining portion and a seating portion of the user holdingmechanism 9 and is controlled by an angle adjusting mechanism controller11. The angle adjusting mechanism controller 11 operates in accordancewith the operation of a remocon (remote controller) 26. Therefore, whenthe user operates the remote controller 26, the angle adjustingmechanism controller 11 controls the reclining angle adjusting mechanism27 in accordance with the operation, so that the reclining angleadjusting mechanism 27 changes an angle of the reclining portion of theuser holding mechanism 9.

As mentioned above, the user operates the remote controller, so that hecan set the angle of the reclining portion of the user holding mechanism9 to an own desired angle, thereby enabling the user to be in the mostrelaxed position by himself.

A low frequency vibrating mechanism 28 is provided in, for example, thereclining portion of the user holding mechanism 9, thereby allowing thelow frequency vibrating mechanism 28 to vibrate in correspondence to anacoustic signal which is supplied through a low pass filter 29, whichwill be explained hereinlater. Thus, the user can feel the acousticsignal.

Further, in an upper portion of the reclining portion of the userholding mechanism 9, for example, a semi-spherical system holdingmechanism 8 (fixing means) constructed so that when the user sits there,a head portion of the user is covered is fixed. A display apparatus 7and a speaker 25 are provided in the system holding mechanism 8.

That is, the display apparatus 7 (video image providing apparatus) isfixed in the system holding mechanism 8 in a manner such that the useris located almost ahead (front surface) of the user in a state where heis held in the user holding mechanism 9. The user holding mechanism 9can hold the user so that an interval between the head portion of theuser and the display apparatus 7 lies within, for instance, 45 cm.

The display apparatus 7 has: a small display panel 14 (display means)which displays a video image supplied from a video audio formingapparatus 10 and is constructed by, for example, a liquid crystaldisplay or the like; and a lens 13 serving as an enlargement opticalsystem for forming a virtual image by enlarging the video imagedisplayed on the display panel 14 and for arranging virtual images whichare observed by the right and left eyes of the user at the same positionon a space. Thus, a video image obtained by enlarging the video imagethat is supplied from the video audio forming apparatus 10 is providedto the user.

The speaker 25 is fixed in the system holding mechanism 8 in a mannersuch that in a state where the user is held by the user holdingmechanism 9, for example, the user is located on almost of the upper,right, or left side (for example, near the ears) or the like of theuser, thereby generating the acoustic signal (audio signal) suppliedfrom the video audio forming apparatus 10. A sound volume can becontrolled by the remote controller 26.

The system holding mechanism 8 is constructed by a device such as an ECD(Electrochromic Display) or the like in which a light transmittance isvariable (hereinafter, properly referred to as a transmittance variabledevice) or the like or is constructed by assembling a liquid crystalshutter or the like into a transparent member, and has a transmittancecontrol mechanism 16 for controlling the transmittance variable device,liquid crystal shutter, or the like. The transmittance control mechanism16 controls the transmittance variable device, liquid crystal shutter,or the like in correspondence to the operation of the remote controller26, thereby allowing an amount of light which enters from the outside tobe changed for the system holding mechanism 8. Therefore, by operatingthe remote controller 26, the user changes the transmittance of thesystem holding mechanism 8, thereby enabling the user to see an externalscene (situation) or preventing the external scene from entering theeyes.

The video audio forming apparatus 10 generates the video image which isdisplayed on the display apparatus 7 and the acoustic signal which isoutputted from the speaker 25. That is, in the embodiment, the videoaudio forming apparatus 10 has a VTR (video tape recorder) 17, a TV(television) tuner 18, and a computer 19. In the VTR 17, a video signaland an audio signal recorded on a video tape are reproduced. In the TVtuner 18, a video signal and an acoustic signal of a predeterminedtelevision broadcasting are received. In the computer 19, a video signaland an acoustic signal are reproduced from a recording medium such as aCD-ROM (Compact Disc—Read Only Memory) or a video signal and an acousticsignal are received from a communication network such as an internet orthe like.

The video signals and acoustic signals obtained by the VTR 17, TV tuner18, and computer 19 are supplied to a selector 21. The selector 21selects any one of outputs of the VTR 17, TV tuner 18, and computer 19and generates in correspondence to the operation of the remotecontroller 26. The video signal selected by the selector 21 is suppliedto the display apparatus 7. The acoustic signal is amplified by anamplifier 24 and is supplied to the speaker 25 and low pass filter 29.The low pass filter 29 extracts a low frequency component of theacoustic signal and supplies to the low frequency vibrating mechanism28.

In the virtual image providing system constructed as mentioned above,for example, in a state where the user is held by the user holdingmechanism 9, when the user operates the remote controller 26 anddesignates any one of the outputs of the VTR 17, TV tuner 18, andcomputer 19, the output (video signal and acoustic signal) is selectedby the selector 21.

The video signal selected by the selector 21 is supplied to the displayapparatus 7 and is displayed on the display panel 14. The video imagedisplayed on the display panel 14 is enlarged by the lens 13 and aresultant virtual image is supplied to the user held by the user holdingmechanism 9. In this manner, the user can observe the virtual image at aremote distance, so that he can feel a space (virtual image space) thatis equivalent or wider than the actual space.

The user can appreciate the virtual image almost without feeling afatigue in a state where he is held by the user holding mechanism 9 anda state where the display apparatus 7 is attached to the head portion orwithout holding it, namely, in a very relaxed state.

In this instance, as mentioned above, by operating the remote controller26, the user can change a transmittance of the system holding mechanism8 covering the head portion through the transmittance control mechanism16. For example, when the transmittance is set to a low value, sincemost of the light from the outside is shut off, the user can immersehimself into the virtual image space. On the contrary, when thetransmittance is set to a high value, the user can appreciate thevirtual image while confirming the ambient situation. On the other hand,for example, in case of gradually reducing the transmittance, the usercan feel a sense as if he was immersed into the virtual image space fromthe actual world.

The acoustic signal selected by the selector 21 is amplified by theamplifier 24 and is supplied to the speaker 25 and is generated.Further, only the low frequency component is extracted from theamplified acoustic signal by the low pass filter 29 and is supplied tothe low frequency vibrating mechanism 28. Thus, the low frequencyvibrating mechanism 28 vibrates in correspondence to the low frequencycomponent of the acoustic signal which is generated from the speaker 25and the user can feel the acoustic signal. That is, in this case, apowerful auditory environment can be provided to the user. A vibratinglevel can be controlled by the remote controller 26.

In the display apparatus 7, a video image (virtual image) in which ahorizontal angle of visibility is equal to or larger than 15° is formed,so that the virtual image with presence (wide virtual image space) isprovided.

Further, from a viewpoint of prevent a flickering of the video image,the video signal which is supplied to the display apparatus 7 is set anon-interlaced signal (progressive video image) (for example, a signalfor a computer, a signal of what is called a clear vision, or the like).

That is, for example, in a television signal according to the NTSC(National Television System Committee) system or the like, since it isinterlace scanned, the user feels a flickering due to the interlace. Onthe other hand, in a non-interlaced signal, the user does not feel sucha flickering (in the case where the television signal according to theNTSC system is displayed on a television receiver having an aspect ratioof (4:3) or the like, it is known that it is necessary for the viewer tobe away from the screen by a distance of about seven times as long as aheight of display screen when a person having an eyesight of 1.0 watchesa video image without feeling a flickering. In this case, however, thehorizontal angle of visibility is equal to about 10° and it is difficultto see the video image with presence. On the other hand, in case of whatis called a laterally wide television receiver or the like having anaspect ratio of (16:9), a horizontal angle of visibility of about 15°can be assured and the video image with presence can be obtained).

In case of constructing the display panel 14 by, for example, a CRT(Cathode Ray Tube) or the like for displaying a video image by scanninga beam, there is a problem as mentioned above. However, in case ofconstructing the display panel by a display having a memory to holdpixel values like a TFT (Thin Film Transistor) liquid crystal display orthe like, an interlaced signal can be also used. In other words, in thiscase, since the pixel values are held in the memory, a flickering of thevideo image is hard to see. Therefore, any one of the interlaced signaland the non-interlaced signal can be used as a video signal.

According to the virtual image providing system in FIG. 1 as mentionedabove, the user can appreciate the virtual image with presence in a veryrelaxed state.

The user holding mechanism 9, system holding mechanism 8, and displayapparatus 7 are so-called integratedly constructed. Since the displayapparatus 7 fixed by the system holding mechanism 8 is arranged at aposition that is very close to the user held in the user holdingmechanism 9 by 45 cm or less as mentioned above, not so a wide space isneeded to install the whole system. That is, a wide virtual image spacecan be provided to the user without occupying a wide space.

Further, in case of arranging the display apparatus 7 at a position awayfrom the user, the display apparatus 7 itself is conspicuous to theuser's eyes and the presence of virtual image is lost. To prevent such aloss of the presence, there is also a method of using the lens 13 of alarge size and enlarging the whole display apparatus 7 in size. However,this method results in an increase in costs and scale of the wholesystem. In case of arranging the display apparatus 7 at a position nearthe user, as mentioned above, it is possible to prevent that thepresence of virtual image is missing and that the costs and scale of thesystem increase.

FIG. 2 shows a constructional example (first constructional example) ofan optical system of the display apparatus 7 in FIG. 1. FIG. 2illustrates the constructional example in case of seeing from the headside of the user held in the user holding mechanism 9.

In the embodiment of FIG. 2, as an enlargement optical system to form avirtual image by enlarging a video image, the display apparatus 7 has alens 13L as (constructing) an optical system for the left eye and a lens13R as an optical system for the right eye in which optical axes aredifferent.

That is, the lens 13R or 13L is, for example, a convex lens having thesame characteristics for providing a virtual image R or L which isobtained by enlarging a video image displayed on a display panel 14R or14L to the right eye or left eye, respectively. Those lenses arearranged on the same plane. That is, the lenses 13R and 13L are arrangedso that their principal planes coincide.

In FIG. 2, O1 or O2 denotes a principal point of the lens 13R or 13L andF1 or F2 indicates a focal point of the lens 13R or 13L. O indicates amiddle point between the principal points O1 and O2.

The display panel 14R or 14L is arranged in a manner such that itscenter point (for example, in the case where the display panels 14R and14L are rectangular, a cross point of diagonal lines of the rectangle,or the like) is located on a straight line OF1 or OF2 connecting themiddle point O and focal point F1 or F2, respectively, and both of themare located on the same plane.

According to the display apparatus 7 constructed as mentioned above, thevideo image displayed on the display panel 14R or 14L is enlarged by thelens 13R or 13L and the light corresponding to the enlarged video imageenters the right eye or left eye, so that the virtual imagecorresponding to the video image is observed by the right eye or lefteye. That is, the virtual image R or L which is formed by the lens 13Ror 13L is observed by the right eye or left eye, respectively.

According to the construction of FIG. 2, although the virtual imagewhich is observed by the right eye or left eye is formed by the lens 13Ror 13L as an individual optical system, those virtual images arearranged at the same position in a 3-dimensional space. That is, thevirtual images which are observed by the right and left eyes of the userare arranged at the same position in the space.

This is because of the following reasons. That is, for example, it isnow assumed that the direction from the principal point O2 to O1 islabelled as a d axis and the optical axial direction (direction from theprincipal point O2 to the focal point F2) of the lens 13L is labelled asan s axis. A center point of the display panel 14L is set to M1,coordinates on its sd plane assume (s1, d1), a center point of thevirtual image L which is formed by the lens 13L is set to M1′, andcoordinates on the sd plane are set to (s1′, d1′). Further, a middlepoint between the focal points F1 and F2 is set to O′.

In this case, as mentioned above, since the display panel 14R or 14Lexists in the same plane and its center point exists on the straightline OF1 or OF2, the display panels 14R and 14L are located at an equaldistance from the principal planes (these are also located in the sameplane as mentioned above) of the lenses 13R and 13L. Therefore, sincethe virtual images R and L also exist in the same plane, if the centerpoints of the virtual images R and L exist on a straight line OO′connecting the middle points O and O′, the virtual images R and L existat the same position.

Since the center point M1 (s1, d1) of the display panel 14L now existson the straight line OF2, the following equation is satisfied.

d1=L/2−L×s1/(2×f)  (1)

where, L denotes a distance between the principal points O1 and O2 and findicates a focal distance of the lens 13L.

On the other hand, the following equation is satisfied by an imageforming formula.

1/f=1/s1−1/s1′  (2)

Since the principal point O2 and center points M1 and M1′ exist on astraight line, the following equation is satisfied.

s1/s1′=d1/d1′  (3)

From the equations (1) to (3), the following equation is derived.

d1′=L/2  (4)

From the equation (4), the center point M1′ of the virtual image Lexists on the straight line OO′.

The optical system constructed by the lens 13L and the optical systemconstructed by the lens 13R are symmetrical with respect to the straightline CO′, so that the center point of the virtual image R also exists onthe straight line OO′.

As mentioned above, since the virtual images R and L exist in the sameplane and their center points exist on the straight line OO′, thevirtual images R and L exist at the same position.

The user, accordingly, can observe the virtual image in a state where avergence of both eyes and an adjustment are matched, namely, in arelaxed state.

The display panels 14R and 14L are designed so that their center pointsare synchronously moved on the straight line OF1 or OF2 so as to beincluded in the same plane, so that the positions where the virtualimages R and L are formed are also moved. The movement of the displaypanel 14R and 14L is performed by, for example, operating the remotecontroller 26 by a stepping motor or the like (not shown). The displaypanels 14R and 14L are moved in a range on the lens 13R side or 13L siderather than the focal point F1 or F2. As mentioned above, this isbecause in order to observe the virtual image of the object, it isnecessary that the object exists at a position near the lens rather thanthe focal distance.

The lenses 13R and 13L are worked so that their outer shapes haverectangular shapes or the like and are enclosed in rectangularparallelepiped lens holders as shown in FIG. 3A. In FIG. 3A, a thicknessδ of boundary portion between the lens holder on the right side in whichthe lens 13R is enclosed and the lens holder on the left side in whichthe lens 13L is enclosed is set to be equal to or less than at least ahuman pupil diameter (generally, it is known that it is equal to about 3to 8 mm or about 2 to 7 mm), thereby preventing the boundary portionfrom being recognized by the user. That is, if the thickness 6 ofboundary portion is set to the pupil diameter or less, the boundaryportion is not formed as an image on the retina and becomes a blurstate, so that the boundary portion can be made hard to be recognized bythe user.

By adhering the lenses 13R and 13L by, for example, a transparentadhesive agent instead of enclosing into the lens holders as shown inFIG. 3A, the thickness of boundary can be made thin as much as possible.

By thinning the thickness of boundary of the lenses 13R and 13L, asshown in FIG. 3B, a lens apparent angle can be sufficiently increased ascompared with an angle of visibility of the virtual image (virtual imageangle of visibility).

The lenses 13R and 13L are constructed so that the whole video image canbe observed from any position so long as it lies within at least a rangewhere the head portion (eyeball) of the user held in the user holdingmechanism 9 can be easily moved.

That is, assuming that the horizontal angle of visibility of the virtualimage assumes α, as shown in a top view diagram of FIG. 4A, a length L1in the horizontal direction of the lenses 13R and 13L is set in a mannersuch that a range (hatched portion in FIG. 4A) (hereinafter, properlyreferred to as a horizontal direction eyeball position allowable range)obtained by excluding a triangle GHP1 from a range which is surroundedby straight lines connecting a point P1 which is a point on the straightline that is parallel with an optical axis passing the boundary betweenthe lenses 13R and 13L and in which an angle formed by the straightlines connecting such a point and the right and left edges of the lenses13R and 13L is equal to a and the right and left edges of the lens 13Ror 13L includes at least a range where the eyeball moves due to themovement of the user.

A side GH of the triangle GHP1 is a portion that is parallel with theprincipal plane of the lens 13 and its length is equal to, for example,an average distance between the pupils of the right and left eyes of theuser.

On the other hand, assuming that the vertical angle of visibility is setto a, as shown in a side elevational view (left side view) of FIG. 4B, alength L2 in the vertical direction of the lenses 13R and 13L is set ina manner such that a range (hatched portion in FIG. 4B) (hereinafter,properly referred to as a vertical direction eyeball position allowablerange) surrounded by straight lines connecting a point P2 which is apoint on the optical axis of the lens 13L (or 13R) and in which an angleformed by the straight lines connecting such a point and the upper andlower edges of the lens 13L is equal to β and the upper and lower edgesof the lens 13L includes at least a range where the eyeball moves due tothe movement of the user.

So long as the eyeballs of the user lie within a range that is common toboth of the horizontal direction eyeball position allowable range andthe vertical direction eyeball position allowable range, even if theuser moves the head portion in the state where he is held by the userholding mechanism 9, he can observe the whole virtual image. Thus, forexample, even if the user unconsciously moves the head portion, asituation such that a part of the virtual image or the whole virtualimage cannot be seen due to such a movement does not occur.

In FIG. 4A, even if the virtual image to be observed by the right eye orleft eye is formed not by the lens 13R or 13L but by the other lens 13Lor 13R by the movement of the head portion by the user, the user canappreciate the whole virtual image.

In principle, as the length L1 in the horizontal direction and thelength L2 in the vertical direction of the lenses 13R and 13L arelonger, the hatched range increases more. That is, when the user movesthe head portion, the range where the whole virtual image can beappreciated is widened more. However, this results in an enlargement insize of the system. It is, therefore, desirable to decide L1 and L2 bykeeping a good balance between the scale of the system and the rangenecessary to appreciate the whole virtual image (for example, about 100mm or the like).

Further, the lenses 13R and 13L don't need to have a shape which issymmetrical with respect to the optical axis. That is, the lenses 13Rand 13L can be constructed so that the right half and the left half haveasymmetrical shapes or the like.

If the right and left eyes of the user are located within the hatchedrange (hereinafter, properly referred to as a whole visible range) inFIG. 4, the whole virtual image can be appreciated as mentioned above.However, if the aberration largely fluctuates depending on the position,although a clear virtual image can be obtained in a small aberrationportion, a blur virtual image is derived in a large aberration portion.

In the display apparatus 7, by constructing the lens 13 (13R and 13L) bya plurality of lenses as shown in FIG. 5, the aberration in the wholevisible range and its fluctuation amount are reduced.

That is, in FIG. 5, the lens arranged at a position that is the closestto the display panel 14 has a larger refractive power than those of theother lenses. The lens arranged at a position that is the farthest fromthe display panel 14, namely, in FIG. 5, the lens arranged at a positionthat is the closest to the user has a smaller refractive power thanthose of the other lenses.

By constructing the lens 13 by a plurality of lenses, since the lightcan be refracted by each of the plurality of lenses, a load per lens canbe lightened. Thus, the aberration of the whole lens 13 can bedecreased. Moreover, by arranging the lens of a large refractive poweron the display panel 14 side, the lens of a small refractive power canbe arranged on the user side. In this case, since the power (refractivepower) of the lens on the user side, namely, eyeball side is small, evenif the pupil is not located on the optical axis of the lens 13, a locusof the light beam hardly changes.

That is, FIG. 5A shows a left side elevational view (or top view) in thecase where the pupil is located on the optical axis. FIG. 5B shows aleft side elevational view in the case where the pupil is not located onthe optical axis. However, the loci (optical paths) of both of the lightbeams hardly change and the light beams are almost converged on thevirtual image surface. Even if the pupil position is deviated, thevirtual image with less aberration can be observed.

In case of constructing the lens 13 by a plurality of lenses as shown inFIG. 5, if a lens having a negative power and in which dispersion ofwavelength is larger than those of the other lenses is included amongthem, a chromatic aberration can be corrected.

In FIG. 5, although the lens 13 is constructed by four lenses,parameters of those four lenses can be set to, for example, thefollowing values.

That is, now assuming that the four lenses are called the first, second,third, and fourth lenses from the display panel 14 side, radii ofcurvature (mm) of the display surface of the display panel, the surfaceof the first lens on the display panel 14 side, the surface on its pupilside, the surface of the second lens on the display panel 14 side, thesurface on its pupil side, the surface of the third lens on the displaypanel 14 side, the surface on its pupil side, the surface of the fourthlens on the display panel 14 side, and the surface on its pupil side areset to, for example, ∞, −273.2355, −43.0090, 156.9532, −158.9318,71.8083, 121.5689, 65.9055, and 61.6620, respectively.

A distance (distance on the optical axis) from the display surface ofthe display panel 14 to the surface of the first lens on the displaypanel 14 side, a distance from the surface of the first lens on thedisplay panel 14 side to the surface on the pupil side, a distance fromthe surface of the first lens on the pupil side to the surface of thesecond lens on the display panel 14 side, a distance from the surface ofthe second lens on the display panel 14 side to the surface on the pupilside, a distance from the surface of the second lens on the pupil sideto the surface of the third lens on the display panel 14 side, adistance from the surface of the third lens to the surface on thedisplay 14 side to the surface on the pupil side, a distance from thesurface of the third lens on the pupil side to the surface of the fourthlens on the display panel 14 side, a distance from the surface of thefourth lens on the display panel 14 side to the surface on the pupilside, and a distance from the surface of the fourth lens on the pupilside to the pupil are set to, for example, 27.0, 18.7626, 0, 11.7904, 0,6.2371, 0, 2.4340, and 50, respectively.

The display panel 14 (14R and 14L) can be constructed by, for example, aself light emitting type device for displaying a video image by a lightemitting device which emits light on a pixel unit basis, a transmissionlight control type device for displaying a video image by controllingthe transmission of the light, a reflection light control type devicefor displaying a video image by controlling the reflection of the light,or the like.

FIG. 6 shows a constructional example of the self light emitting typedevice.

The self light emitting type device is constructed by a light emittingunit comprising a number of light emitting elements corresponding topixels and a control unit for controlling the light emission of eachlight emitting element. Since the self light emitting type device has asimple construction and a light weight and a self light emission isperformed, dependency on the angle of visibility is small. Thus, in caseof constructing the display panel 14 by the self light emitting typedevice, the weight of system can be reduced. Further, even in case ofseeing the video image from the oblique direction, a clear video imagecan be observed. As a self light emitting type device, for instance,there is a CRT or the like.

FIG. 7 shows a constructional example of the transmission light controltype device.

The transmission light control type device is constructed by a backlightfor emitting light and a transmission light control unit for controllingthe transmission of the light from the backlight on a pixel unit basis.According to the transmission light control type device, by adjusting anamount of light emitted by the backlight, a necessary brightness can beeasily obtained. On the other hand, according to the foregoing selflight emitting type device, it is necessary to adjust the light amountof each light emitting element. Further, in the self light emitting typedevice, there is a limitation of the light emission amount depending onthe device itself. In the transmission light control type device,however, since the backlight is what is called a mere illumination,backlights of various light emission amounts exist. Therefore, by merelyexchanging the backlight, a video image of a desired brightness can bedisplayed.

The transmission light control type device is suitable for a case ofconstructing the display panel 14 in a relatively flat shape.

As a transmission light control type device, for example, there are aliquid crystal display and the like.

FIG. 8 shows a constructional example of the display panel 14 in case ofusing the reflection light control type device.

In this case, light is emitted from the light source and is reflected bya half mirror and enters a reflecting type device. The reflecting typedevice is constructed by arranging a number of elements corresponding tothe pixels in a plane shape and a reflectance of each element iscontrolled in correspondence to the video signal. Therefore, the lightentering the reflecting type device is reflected by each element at thereflectance corresponding to the video signal. The video image asreflection light transmits the half mirror and enters the eyeballs ofthe user through the lens 13. Thus, the virtual image is observed by theeyeballs of the user.

In the reflection light control type device, therefore, an effect thatis equivalent to the effect such that the video image is opticallydisplayed in the reflecting type device is obtained.

In the foregoing transmission light control type device (FIG. 7), acontrol mechanism to control the transmittance fundamentally needs to beprovided at the boundary of each pixel of the transmission light controlunit. The transmittance slightly deteriorates due to such a mechanism.Therefore, when the number of pixels is increased, an area ratio of thecontrol mechanism increases and the whole transmittance deteriorates.Therefore, to obtain a predetermined light amount, it is necessary toalso increase the light amount of the backlight in association with anincrease in number of pixels. On the other hand, in the reflection lightcontrol type device (FIG. 8), since a control mechanism to control thereflectance of the reflecting type device can be provided on the sideopposite to the reflecting surface, the number of pixels can be easilyincreased.

When the display apparatus 7 is constructed so that the display panels14R and 14L are located in front of the user as shown in FIG. 2, even ifthe system holding mechanism 8 (FIG. 1) transmits the light, a field ofview is obstructed by the display panels 14R and 14L. Therefore, anexternal situation (scene) corresponding to the obstructed range of thefield of view cannot be confirmed.

To prevent the field of view of the user from being obstructed,therefore, the display apparatus 7 can be constructed as shown in, forexample, FIG. 9.

That is, FIG. 9 shows a second constructional example of the displayapparatus 7.

In this case, the lens 13 and display panel 14 are not arranged in frontof the user but is arranged in the upper portion (direction over thehead of the user) so as not to obstruct the field of view. The videoimage displayed on the display panel 14 is enlarged by the lens 13 andthe light serving as an enlarged video image enters the half mirror. Thelight from the lens 13 is reflected by the half mirror and the reflectedlight enters the eyeballs of the user. Thus, the virtual image isobserved by the eyeballs of the user.

In the embodiment of FIG. 9, a liquid crystal shutter is provided on theside of the half mirror opposite to the side which faces the user,thereby allowing the light from the outside to enter the half mirrorthrough the liquid crystal shutter. Further, the light transmits thehalf mirror and enters the eyeballs of the user. Thus, the user canobserve (confirm) the situation (scene) of the front side of himself ina state where it is overlaid to the virtual image.

The liquid crystal shutter changes an amount of light which transmitstherein in correspondence to the operation of the remote controller 26(FIG. 1). Thus, the user can observe the virtual image with a goodbalance of brightness and the external scene.

In this case, since the external situation can be confirmed in a statein which it is overlaid to the virtual image, the user can appreciatethe virtual image in a relaxed state (without feeling an anxiety due toa fact that he cannot see the outside).

In the above description, the enlargement optical system such that thevirtual image is formed by enlarging the video image displayed on thedisplay panel 14 and the virtual images to be observed by the right andleft eyes of the user are arranged at the same position in the space hasbeen constructed by using the lens 13 as a convex lens. However, theenlargement optical system can be also constructed by using other lenssuch as a concave surface mirror or the like besides the convex lens.

FIG. 10 shows a constructional example (third constructional example) incase of using a concave surface mirror 31 (31L and 31R) as anenlargement optical system of the display apparatus 7. FIG. 10A shows afront view when the display apparatus 7 is seen from the user side(surface side which faces the user at the time of using). FIG. 10B showsa cross sectional view of its side surface (for example, side surface onthe left side when it is seen from the surface side which faces the userat the time of using).

In the embodiment, a half mirror is arranged so as to face the user uponusing and, further, the concave surface mirror 31 (31L and 31R) isarranged on the rear side. The display panel 14 (14L and 14R) isarranged in the upper portion (therefore, direction over the head of theuser) of the half mirror.

In the display apparatus 7 constructed as mentioned above, the videoimage displayed on the display panel 14 is reflected by the half mirrorand enters the concave surface mirror 31. In the concave surface mirror31, the video image from the half mirror is enlarged by being reflected.The enlarged video image transmits the half mirror and enters theeyeballs of the user. Thus, the virtual image is observed (perceived) bythe eyeballs of the user. The virtual images which are observed by theright and left eyes of the user are arranged at the same position in thespace in a manner similar to the case of FIG. 2.

A point (half mirror reflection equivalent position) that is equivalentto the principal point or focal point of the concave surface mirror 31Ris formed on a straight line which exists in the plane perpendicular tothe half mirror and which is perpendicular to an optical axis of theconcave mirror surface 31R. The point which is equivalent to theprincipal point or focal point is referred to as P_(FR) or P_(OR).Similarly, with regard to the concave surface mirror 31L as well, apoint which is formed by the half mirror and is equivalent to theprincipal point or focal point is expressed as P_(FL) or P_(OL). Amiddle point between the points P_(OR) and P_(OL) which is equivalent tothe principal point is shown by P.

In this case, each of the display panels 14R and 14L synchronously movesso that the center point is located on a straight line connecting thepoints P_(FR) and P or a straight line connecting the points P_(FL) andP and is included in the same plane, so that the position where thevirtual image is formed moves. The movement of the display panels 14Rand 14L is performed by, for example, a stepping motor (not shown) byoperating the remote controller 26. Each of the display panels 14R and14L moves in a range on the half mirror side rather than the pointP_(FR) or P_(FL) that is equivalent to the focal point, thereby enablingthe user to observe the virtual image.

In case of constructing the enlargement optical system by the concavesurface mirror as mentioned above, since the concave surface mirror canbe relatively easily made thinner than the lens, the weight of systemcan be reduced.

In the case where the concave surface mirror 31 is formed by the halfmirror and, further, as shown in FIG. 10B, the liquid crystal shutter orthe like which can change the light transmission is provided behind theconcave surface mirror 31, the light from the outside can be allowed toenter the eyeballs of the user through the liquid crystal shutter,concave surface mirror 31, and half mirror. Further, in this case, theamount of light which enters the eyeballs can be adjusted by controllingthe liquid crystal shutter. In this case, therefore, in a manner similarto the case in FIG. 9, the user can observe the situation in front ofhimself in a state where it is overlaid to the virtual image and,further, can observe the virtual image with a good balance of brightnessand the external scene.

In the above example, the enlargement optical system has beenconstructed by the optical system (lens 13L or concave surface mirror31L) for the left eye and the optical system (lens 13R or concavesurface mirror 31R) for the right eye which have the different opticalaxes. However, the enlargement optical system can be also constructed byonly an optical system with one optical axis.

That is, FIG. 11 is a top view showing a constructional example (fourthconstructional example) of the display apparatus 7 in case ofconstructing the enlargement optical system by one convex lens.

In this case, the lens 13 has a diameter larger than that of, forinstance, the lens 13R (or 13L) shown in FIG. 2 and (the center of) onedisplay panel 14 is arranged at a position which exists on its opticalaxis and is nearer than the focal distance.

In the display apparatus 7 constructed as mentioned above, the videoimage displayed on the display panel 14 is enlarged by the lens 13. Theenlarged image enters the eyeballs of the user. Thus, the virtual imageis observed (perceived) in the eyeballs of the user.

FIG. 12 shows a constructional example (fifth constructional example) ofthe display apparatus 7 in case of constructing the enlargement opticalsystem by one concave surface mirror. FIG. 12A shows a cross sectionalview of its top view. FIG. 12B shows a cross sectional view of its sideview.

In this case, the concave surface mirror 31 has a diameter larger thanthat of, for instance, the concave surface mirror 31R (or 31L) shown inFIG. 10 and a half mirror is arranged on the reflecting surface side.The display panel 14 is arranged in the upper portion of the halfmirror. In a manner similar to the case described in FIG. 10, itsarranging position is set to the half mirror side rather than the pointthat is equivalent to the focal point of the concave surface mirror 31which is formed by the half mirror.

In the display apparatus 7 constructed as mentioned above, the videoimage displayed on the display panel 14 is reflected by 90° by the halfmirror and enters the concave surface mirror 31. In the concave surfacemirror 31, the video image from the half mirror is enlarged by beingreflected. The enlarged video image transmits the half mirror and entersthe eyeballs of the user. Thus, a virtual image is observed in theeyeballs of the user.

As shown in FIGS. 11 and 12, in case of constructing the enlargementoptical system by only the optical system of one optical axis, since onevirtual image is observed by the right and left eyes, a vergence of botheyes and its adjustment perfectly coincide. Thus, the user canappreciate the virtual image almost without feeling a fatigue (even incase of constructing the enlargement optical system by the opticalsystem (lens 13L and concave surface mirror 31L) for the left eye andthe optical system (lens 13R or concave surface mirror 31R) for theright eye which have different optical axes, in the embodiment, asdescribed in FIG. 2, since the virtual images which are observed by theright and left eyes of the user are arranged at the same position in thespace, the user can appreciate the virtual image almost without feelinga fatigue).

Since the lens 13 or concave surface mirror 31 in the embodiment of FIG.11 or 12 has a large diameter, even if the user slightly moves the headportion, the whole virtual image can be appreciated without missing thevirtual image.

As compared with the case of constructing the enlargement optical systemby only the optical system of one optical axis, however, by constructingthe enlargement optical system by the optical system of two opticalaxes, namely, by the optical systems for the right and left eyes, a sizeand an aberration per lens or concave surface mirror can be set to asmall value.

Subsequently, FIG. 13 is a cross sectional view of the left side viewshowing further another constructional example (sixth constructionalexample) of the display apparatus 7. In the embodiment, the displayapparatus 7 is constructed in a manner similar to the case in FIG. 2except that a cylindrical lens 41 (curving means) is newly providedbetween the lens 13 and display panel 14 as an optical part constructingthe enlargement optical system.

In the embodiment of FIG. 13, since the surface of the cylindrical lens41 which faces the lens 13 is dented in a cylindroid, its center portionis thin and its upper and lower portions are thick. In this case, ascompared with an optical distance from a position near the center (nearthe center in the vertical direction, here) of the display panel 14 tothe principal plane of the lens 13, an optical distance from itsperiphery (upper and lower portions of the display panel 14, here) tothe principal plane is shorter.

That is, as shown in FIG. 14, when an object having a refractive indexof n and a thickness of d is put between points A and B in which anoptical distance in the air is equal to L, an optical distance (distanceas an air conversion value) between the points A and B through theobject is generally equal to L−d×(n−1)/n and is usually shorter ascompared with the case (L) where no object is interposed.

In this case, therefore, the surface on which the virtual image formedby the lens 13 is arranged is curved in the upper/lower direction(vertical direction) in which the upper and lower portions are closer tothe user side rather than a portion near the center as shown in FIG. 13.

In this case, the user can be made feel as if he was surrounded by thevirtual image, so that a virtual image with larger presence can beprovided.

In the embodiment of FIG. 13, although the virtual image in which theupper and lower portions are curved can be obtained, by rotating thecylindrical lens 41 by 90° from the position in case of FIG. 13 andarranging, a virtual image in which the right and left sides are curved(virtual image which is curved in the horizontal direction) can beobtained.

By using, for example, a lens which is dented like a sphere(plano-concave lens) as a lens 41 instead of a lens which is dented in acylindroid (cylindrical lens), a virtual image such that it issurrounded from the upper, lower, right, and left directions can beprovided. Further, by forming the lens which is used as a lens 41 into adesired shape, a virtual image which is curved in such a desired shapecan be obtained.

In the embodiment of FIG. 13, although the video image is enlarged bythe convex lens (lens 13), the concave surface mirror can be also usedto enlarge the video image.

In FIG. 2 or the like, for example, the lens 13L for the left eye andthe lens 13R for the right eye are provided as enlargement opticalsystems, two display panels 14L and 14R are provided, the video image ofthe display panel 14L is enlarged by the lens 13L, and the video imageof the display panel 14R is enlarged by the lens 13R, respectively.However, it is also possible to construct in a manner such that thenumber of display panels to display video images is set to one and thevideo image which is displayed by the display panel is separatelyallowed to enter the optical system for the left eye and the opticalsystem for the right eye, thereby providing a virtual image to the user.

FIG. 15 is a top view showing a constructional example (seventhconstructional example) of such a display apparatus 7.

The display panel 14 is arranged on the center line of the positionswhere the right and left eyes of the user are arranged at the time ofusing. A video image which is displayed by the display panel 14 enters ahalf mirror 51. The half mirror 51 (entering means) transmits a part ofthe video image on the display panel 14 and bends the remaining portionof the video image by 90° and reflects, thereby allowing the video imagewhich is displayed by the display panel 14 to individually enter theoptical system for the left eye and the optical system for the righteye.

That is, the video image transmitting the half mirror 51 enters a mirror52, by which it is reflected by 90° and enters a mirror 53. In themirror 53, the video image from the mirror 52 is reflected by 90° andenters the lens 13R. The lens 13R enlarges the video image from themirror 53 and allows the video image to enter the right eye.

On the other hand, the video image reflected by the half mirror 51 isreflected by 90° by a mirror 54 and enters the lens 13L. The lens 13Lenlarges the video image from the mirror 54 and allows the video imageto enter the left eye.

As mentioned above, the virtual image in which the video image displayedon one display panel 14 is enlarged by the lens 13L or 13R isrespectively observed by the left eye or right eye of the user.

In FIG. 15, although the convex lenses (lens 13L and 13R) have been usedas enlargement optical systems, a concave surface mirror can be alsoused as an enlargement optical system.

That is, FIG. 16 shows a constructional example (eighth constructionalexample) of the display apparatus 7 in case of using the concave surfacemirror. FIG. 16A shows a front view of the display apparatus 7. FIG. 16Bshows a side elevational view of the left side view.

In this case, a video image which is displayed by the display panel 14arranged in the direction over the head of the user enters a half mirror61. The half mirror 61 (entering means) transmits a part of the videoimage on the display panel 14 and reflects the remaining portion of thevideo image by 90°, thereby allowing the video image which is displayedby the display panel 14 to individually enter the optical system for theleft eye and the optical system for the right eye.

That is, the video image transmitting the half mirror 61 enters a mirror64, by which it is reflected by 90° and enters a mirror 65. In themirror 65, the video image from the mirror 64 is reflected by 90° andenters a half mirror 63. In the half mirror 63, the video image from themirror 65 is reflected by 90° and enters the concave surface mirror 31R.In the concave surface mirror 31R, the video image entering there isenlarged. The enlarged video image transmits the half mirror 63 andenters the right eye.

On the other hand, the video image reflected by the half mirror 61 isreflected by 90° by a mirror 62 and enters the half mirror 63. In thehalf mirror 63, the video image from the mirror 62 is reflected by 90°and enters the concave surface mirror 31L. In the concave surface mirror31L, the video image entering there is enlarged. The enlarged videoimage transmits the half mirror 63 and enters the left eye.

As mentioned above, in the left eye or right eye of the user, thevirtual image in which the video image displayed on one display panel 14is enlarged by the concave surface mirror 31L or 31R is observed,respectively.

In case of constructing the display apparatus 7 by one display panel 14as mentioned above, as compared with the case of using two displaypanels 14R and 14L, the system can be constructed with low costs.Further, in case of using the two display panels 14R and 14L, there canbe a rare case where a difference between picture qualities of imageswhich are observed by the right and left eyes occurs due to a variationin their characteristics. However, in case of constructing the displayapparatus 7 by one display panel 14, such a picture quality differencedoes not occur. Thus, the user does not feel a fatigue which is causedbecause of the presence of the difference between the picture qualitiesof the images which are observed by the right and left eyes.

FIG. 17 shows a construction of the second embodiment of a virtual imageproviding system to which the invention is applied. The virtual imageproviding system is constructed in a manner similar to the case in FIG.1 except that a video image forming apparatus 70R for the right eye anda video image forming apparatus 70L for the left eye are provided inplace of the video audio forming apparatus 10 (in FIG. 17, however, apart (for example, the user holding mechanism 9, portions regarding theprocesses of the acoustic signal, and the like) is not shown in FIG.17).

That is, in FIG. 1, a two-dimensional (plane) virtual image has beenprovided by allowing the virtual image with respect to the video imagewhich is generated by one video audio forming apparatus 10 to beobserved by both of the right and left eyes of the user. However, in theembodiment of FIG. 17, a stereoscopic virtual image is provided byallowing a virtual image with regard to a video image which is generatedby the video image forming apparatus 70R for the right eye or the videoimage forming apparatus 70L for the left eye to be observed by the righteye or left eye of the user, respectively.

Specifically speaking, in a VTR 71R or 71L, a video tape on which astereoscopic video image using a binocular parallax has been recorded isreproduced. The video image for the right eye or the video image for theleft eye is outputted to a selector 74R or 74L, respectively. In the VTR71R and 71L, sync signals can be mutually transmitted and received, sothat the video image for the right eye or the video image for the lefteye is generated from each VTR in a synchronized state, respectively.

In a computer 72R or 72L, a video image for the right eye or left eye bycomputer graphics for providing a stereoscopic video image using thebinocular parallax is formed and outputted to the selector 74R or 74L,respectively. The computer 72R and 72L are connected by a predeterminedcommunication line such as a line of Ethernet or the like, so that thevideo image for the right eye and the video image for the left eye areoutputted from the computers in a synchronized state, respectively.

Even in another image forming apparatus 73R or 73L, a video image forthe right eye or left eye constructing a stereoscopic video image usingthe binocular parallax is formed and is outputted to the selector 74R or74L in a synchronized state.

In the selector 74R, an output of any one of the VTR 71R, computer 72R,and other image forming apparatus 73R is selected. The selected output,namely, the video image for the right eye is supplied to the displaypanel 14R. The selector 74L is synchronized with the selector 74R,selects the output corresponding to the one of the VTR 71L, computer72L, and other image forming apparatus 73L which was selected by theselector 74, and supplies the selected output, namely, the video imagefor the left eye to the display panel 14L.

The display of the display panel 14R or 14L is enlarged by the lens 13Ror 13L and enters the right eye or left eye of the user. Thus, in theright eye or left eye of the user, a virtual image obtained by enlargingthe video image for the right eye or left eye is observed, respectively,so that a stereoscopic video image using the binocular parallax isprovided to the user.

In this case, the left eye or right eye of the user is directed towardeach virtual image for the right eye or left eye. Further, its focusingcontrol is also executed so as to be matched with the virtual image forthe right eye or left eye. Therefore, the user can observe thestereoscopic video image almost without feeling a fatigue.

In other words, as a conventional system for appreciating a stereoscopicvideo image, for example, as shown in FIG. 18, there is a system suchthat polarizing filters of different polarizing directions are installedto two projectors and the light of each projector is irradiated to thescreen through the polarizing filter, thereby displaying a video imagefor the right eye (right-eye video image) and a video image for the lefteye (left-eye video image).

According to this system, the user observes the video image for theright eye or the video-image for the left eye by the right eye or lefteye through the polarizing glasses corresponding to each of thepolarizing filters installed to the two projectors, so that astereoscopic video image which is floating from the screen toward theuser side is provided.

In this case, therefore, although the right eye or left eye of the useris directed toward the video image for the right eye or left eye, thefocusing control is performed so as to be matched with the video imageon the screen instead of a stereoscopic video image. Since the focusingcontrol is not performed to the stereoscopic video image position, theuser feels a large fatigue in order to appreciate a stereoscopic videoimage.

On the other hand, in case of FIG. 17, the left eye or right eye of theuser is directed toward the virtual image for the right eye or left eyeand the focusing control is also performed so as to be matched with thevirtual image which is at present seen. Therefore, the user can observea stereoscopic video image almost without feeling a fatigue.

In the embodiment of FIG. 17, although the lenses 13R and 13L as convexlenses have been used as enlargement optical systems, a stereoscopicvideo image can be also provided even by using a concave surface mirrorin a manner similar to the case in FIG. 17.

In the embodiment of FIG. 1, although the display apparatus 7 has beenfixed in the semispherical system holding mechanism 8 fixed in the userholding mechanism 9, for example, the display apparatus 7 can be alsofixed to the other end of an arm stand 81 in which one end is fixed tothe user holding mechanism 9 as shown in FIG. 19.

As shown in FIG. 20, cylindroid hinge portions are provided in severalportions of the arm stand 81. Each hinge portion is rotatable around itscenter axis (straight line passing through the center of two cylindroidbottom surfaces) as a center.

In this case, therefore, the user moves the display apparatus 7 to adesired position and can appreciate a virtual image.

Although not particularly mentioned in the above description, in FIG. 1,for example, the system holding mechanism 8 can rotate upward around aportion connected to the user holding mechanism 9 as a center. In thiscase, the user can easily seat himself onto the user holding mechanism9.

In the above case, the user holding mechanism 9 has been set to a chair,sofa, or the like. However, for example, the user holding mechanism 9can be also replaced to other devices such as a bed in which the usercan relax or the like.

Further, in the above case, although the display apparatus 7 has beenfixed to the user holding mechanism 9, the display apparatus 7 can bealso detachably attached to the user holding mechanism 9. In this case,the removed display apparatus 7 can be fixed to a rod-shaped stand andbe used as shown in, for example, FIG. 21A or the display apparatus 7can be fixed to the other end of an arm stand in which one end is fixedto a desk or the like by a fixing hardware or the like and can be usedas shown in FIG. 21B.

The user holding mechanism 9 can be vibrated or inclined, for example,in the upper, lower, right, and left directions and in the front andrear directions in an interlocking relation with the virtual image to beappreciated by the user. For example, in case of moving the user holdingmechanism 9 in an interlocking relation with a sky video image, a senseas if the user actually was in an airplane can be given to the user.

In the case where the display apparatus 7 is fixed to an object otherthan the user, for example, when the user moves, a relative positionalrelation between the pupil of the user and the ocular lenses serving aslenses 13L and 13R constructing the enlargement optical systems changes.Therefore, it is necessary to keep an interval (eye relief) in a mannersuch that even if the user moves in the optical axial direction to acertain degree, the pupil of the user does not come into contact withthe ocular lens. On the other hand, since there is a case where the userof a low eyesight uses the display apparatus 7 with the glasses held, itis also necessary to construct such that even if the user with theglasses moves in the optical axial direction to a certain degree, theglasses do not come into contact with the ocular lens. In considerationof the user with glasses as well, it is necessary to set the intervalbetween the pupil of the user and the ocular lens, namely, eye relief toa further long value.

When the user moves in the direction perpendicular to the optical axis,although the pupil position of the user is deviated from the opticalaxis, it is desirable to use the ocular lens having high performance ofa large allowance amount of the deviation of the pupil position suchthat a video image (virtual image) of high resolution can be providedeven in such a state.

Further, hitherto, as display panels 14L and 14R, the number of pixelsin the lateral×vertical directions are generally equal to about 640×480(VGA). However, in recent years, a display having the number of pixelssuch as 1024×768 (XGA), 1600×1200 (UXGA), 1920×1080 (HDTV), or the likeis becoming a general display because of a demand for realization ofhigh picture quality or the like. In association with it, as an ocularlens as well, a lens having higher resolution and a wide angle of viewis necessary.

However, a request to make a length of eye relief long and a request toincrease the allowance amount of the deviation of the pupil position arecontradictory requests. Further, those requests and a request to raisethe resolution and a request to widen the angle of view are alsocontradictory requests.

If the focal distance of (the whole system of) the ocular lens is madelong, even in case of the same construction, the eye relief can be madelong and, further, the allowance amount of the deviation of the pupilposition can be enlarged.

However, in the case where the size of video image is constant, sincethe angle of view is inversely proportional to the focal distance, ifthe focal distance of the ocular lens is made long, the angle of view isnarrowed and the presence is missing.

Although the angle of view can be increased by reducing the focaldistance of the ocular lens, in this case, the eye relief becomes shortand the allowance amount of the deviation of the pupil position is alsodecreased. Further, when the angle of view is increased, an astigmatism,an image surface distortion, a distortion aberration, a magnificationchromatic aberration, or the like increases and it is difficult toassure adequate resolution.

FIG. 22, accordingly, shows a constructional example of the firstembodiment of the ocular lenses which are used as lenses 13L and 13Rconstructing the enlargement optical systems.

As mentioned above, a request to make the eye relief of the ocular lenslong and a request to increase the allowance amount for the deviationamount of the pupil position are contradictory requests. It is,therefore, necessary to set the eye relief and the allowance amount ofthe deviation of the pupil position to values which can be practicallypermitted in consideration of the balance between them.

In the ocular lens of the first embodiment in FIG. 22 (the same shallalso similarly apply to ocular lenses in embodiments, which will beexplained hereinlater), the eye relief is set to, for example, 35 mm(millimeters) or more and the allowance amount of the deviation of thepupil position is set to, for example, ±9 mm. Further, the angle of viewis set so that the horizontal angle of view (total angle) of 35° or moreand the diagonal field angle (total angle) of 40° or more can beassured.

For example, in binoculars or the like, the eye relief is generally setto about 20 mm. However, the eye relief is set to 35 mm or more here ina manner such that in the case where the ocular lens is used in thedisplay apparatus 7 fixed to an object other than the user as mentionedabove, even if the user with glasses moves to a certain degree in theoptical axial direction, the glasses do not come into contact with theocular lens.

Since the horizontal angle of view where the user feels presence isusually equal to 30° or more, the horizontal angle of view is set to35°.

In FIG. 22, the ocular lens is made up of a (5 elements in 4 groups)lens. That is, the ocular lens (optical system) is constructed bysequentially arranging a first lens group 101, a second lens group 102,a third lens group 103, and a fourth lens group 104 in accordance withthis order from the pupil side. In FIG. 22, for example, a screen towhich an image for forming a virtual image is projected, a display panelto display the video image for forming the virtual image, or the like isdisposed on the right side of the fourth lens group 104. By seeing theimage from the left side of the first lens group 101, the virtual imagecan be observed.

The first lens group 101 (first lens group) is constructed by joining alens 111 as a positive lens and a lens 112 as a negative lens. The lens111 is arranged on the pupil side and the lens 112 is arranged on theside (screen side) opposite to the pupil, respectively.

The second lens group 102 (second lens group) is constructed by a lens121 as a positive lens. Further, a shape coefficient of the second lensgroup 102 has a value larger than 0.5. That is, now assuming that aradius of curvature of the surface on the pupil side of the second lensgroup 102 is set to r4 and a radius of curvature of the surface on theside (screen side) opposite to the pupil side is set to r5,respectively, a shape coefficient sf₂ of the second lens group 102 isexpressed by the following equation.

sf ₂=(r5+r4)/(r5−r4)  (5)

The second lens group 102 is constructed so that the shape coefficientsf₂ satisfies the following relational expression.

0.5<sf₂  (6)

The reason why the shape coefficient of the second lens group 102 is setto the value larger than 0.5 is because if it is equal to a value of 0.5or less, an astigmatism is large and resolution in an intermediateregion between the center and the edge of a virtual image which isobserved through the ocular lens as shown in a hatched region in FIG. 23deteriorates due to a drop of resolution of the ocular lens.

It is desirable to set the shape coefficient of the second lens group102 to a value larger than 0.5 and it is not a situation that it cannotbe set to a value of 0.5 or less.

The third lens group 103 (third lens group) is also constructed by alens 131 as a positive lens.

The fourth lens group 104 (fourth lens group) is constructed by a lens141 as a negative lens.

Among the foregoing first to fourth lens groups 101 to 104, in FIG. 22,only a surface 131A on the pupil side of the lens 131 constructing thethird lens group 103 is set to an aspherical surface. Further, in thiscase, now assuming that a quartic aspherical coefficient of the surface131A on the pupil side of the third lens group 103 is set to a₃₁ and thefocal distance of the whole system of the ocular lens is set to f and apredetermined coefficient is set to k₃₁, respectively, the coefficientk₃₁ is set so as to satisfy the following relational expression.

−1.3<k₃<0.6

where,

a ₃₁=(k ₃₁ /f)³  (7)

This is because when the coefficient k₃₁ is equal to or less than −1.3,an image surface in the hatched intermediate region in FIG. 23 (imagesurface in the meridional direction) is excessively bent in the positivedirection, and when the pupil is moved, a coma aberration increases inthe peripheral (edge) portion of the picture plane of the video image,and the resolution eventually deteriorates. On the other hand, this isbecause when the coefficient k₃₁ is equal to or larger than 0.6, theimage surface of the peripheral portion of the picture plane of thevideo image is excessively bent in the negative direction and theresolution deteriorates.

The quartic aspherical coefficient of the lens defines a sag amount ofthe aspherical surface of the lens together with a sextic asphericalcoefficient. Now, assuming that the sag amount is equal to Z and thequartic or sextic aspherical coefficient is labeled as a or b,respectively, the sag amount Z is expressed by the following equation.

Z=ch ²/(1+(1−(1+K)c ² h ²)^(½))+ah ⁴ +bh ⁶  (8)

where, c denotes a curvature at a vertex of the surface, h indicates aheight from the optical axis, and K shows a conical coefficient,respectively. It is now assumed that K=0.

It is not limited to a condition such that the coefficient k₃₁ cannot beset to a value out of the range shown in the relational expression (7).However, in case of setting it to a value out of the range of therelational expression (7), the performance of the ocular lens is lowerthan the following performance.

That is, in the first embodiment of the ocular lens shown in FIG. 22(the same shall also similarly apply in embodiments of ocular lenses,which will be explained hereinlater), three optical paths are collectedas one set and five sets of optical paths A to E are shown. However, forexample, now considering the three optical paths on the optical axis,these three optical paths sequentially show the upper light beam, mainlight beam, and lower light beam in accordance with the order from thetop, respectively.

In the case where the pupil exists on the optical axis, a range when adifference between the lateral aberrations of the upper light beam andthe lower light beam on the image surface is equal to or larger than 2minutes 50 seconds (=0.0472°) is set to a range where the resolution ofthe ocular lens deteriorates.

That is, when the video image (virtual image) is observed through theocular lens, it is desirable that the pixels of the observation videoimage can be distinguished. In this case, it is required that each lightbeam such as upper light beam, lower light beam, or the like whichpasses through the ocular lens forms an image with an aberration of 1 to2 pixels or less. On the other hand, it is now assumed that, forexample, a virtual image of a video image of high resolution such as1600×1200 pixels (lateral×vertical) or the like is observed. Now,assuming that the horizontal angle of visibility is equal to or largerthan 30°, for instance, 35°, a case where the difference between thelateral aberrations of the upper and lower light beams is equal to 2minutes 50 seconds for the horizontal angle of visibility of 35°corresponds to the presence of resolution of 1/741 for the horizontalangle of view of 35°. This resolution becomes resolution correspondingto about two pixels in the video image constructed by 1600×1200 pixels.

Therefore, in the case where the video image constructed by 1600×1200pixels is observed while keeping the horizontal angle of view of 35°, iftwo pixels cannot be distinguished, this state denotes that theresolution deteriorates.

A construction when the pupil exists on the optical axis is as mentionedabove. However, in the case where the pupil does not exist on theoptical axis (however, the case where the pupil exists in a range of ±9mm from the optical axis as an allowance amount of the deviation of thepupil mentioned above), with respect to a falling-down of the imagesurface, a state when the difference between the lateral aberrations ofthe upper and lower light beams on the image surface is equal to orlarger than 4 minutes denotes the range where the resolutiondeteriorates. As for the coma aberration, a state when at least one ofthe difference between the lateral aberrations of the upper light beamand the main light beam and the difference between the lateralaberrations of the lower light beam and the main light beam is equal toor larger than 4 minutes indicates the resolution deteriorating range.

When the coefficient k₃₁ is out of the range of the relationalexpression (7), the resolution deteriorates because of the meaning asmentioned above. Conditions regarding the aspherical coefficient, whichwill be explained hereinlater, are also set so as not to deteriorate theresolution in view of the meaning as mentioned above.

The conditions have been set here such that in the case where the videoimage constructed by 1600×1200 pixels is observed while keeping thehorizontal angle of visibility of 35°, two pixels can be distinguishedeven in the worst case. However, more preferably, the conditions can beset so that one or less pixel can be distinguished. It is sufficient toset the difference between the lateral aberrations between the upperlight beam and the lower light beam to one minute 20 seconds (0.022°) orless.

In the case where the coefficient k₃₁ is set to a value, for example,−0.800 in the intermediate range of the range shown in the relationalexpression (7), if each parameter of the ocular lens in FIG. 22 is setso that the shape coefficient sf₂ of the second lens group 102 satisfiesthe relational expression (6), for example, the following equations areobtained.

 r0=∞d0=35.000000

r1=50.24994 d1=19.437488 nd1=1.578294 νd1=62.6745

r2=−41.86735 d2=3.000000 nd2=1.750353 νd2=32.8672

r3=392.33990 d3=0.100000

r4=38.58461 d4=14.577210 nd4=1.487000 νd4=70.4000

r5=578.24030 d5=14.098421

r6=38.98957 d6=9.615117 nd6=1.600080 νd6=61.3702

r7=−138.62195 d7=8.369858

r8=−31.64800 d8=3.000000 nd8=1.755000 νd8=27.6000

r9=78.58062

a ₃₁=−0.522192×10⁻⁵

b ₃₁=−0.715067×10⁻⁸

f=46.112  (9)

where, r0 to r9 denote radii of curvature (mm) in the pupil surface, thesurface on the pupil side of the lens 111, the surface on the screenside of the lens 111 (surface on the pupil side of the lens 112), thesurface on the screen side of the lens 112, the surface on the pupilside of the lens 121, the surface on the screen side of the lens 121,the surface on the pupil side of the lens 131, the surface on the screenside of the lens 131, the surface on the pupil side of the lens 141, andthe surface on the screen side of the lens 141, respectively. d0 denotesa distance (eye relief) (mm) from the pupil to the ocular lens, namely,to the lens 111 of the first lens group 101. d1 to d8 indicate athickness of the lens 111, a thickness of the lens 112, an air gapbetween the lenses 112 and 121, a thickness of the lens 121, an air gapbetween the lenses 121 and 131, a thickness of the lens 131, an air gapbetween the lenses 131 and 141, and a thickness (mm) of the lens 141,respectively. Further, nd1, nd2, nd4, nd6, or nd8 denotes a refractiveindex in a d line of a nitride material of each of the lenses 111, 112,121, 131, and 141, respectively. νd1, νd2, νd4, νd6, or νd8 denotes anAbbe number in the d line of the nitride material of each of the lens111, 112, 121, 131, or 141, respectively. a₃₁ or b₃₁ denotes the quarticor sextic aspherical coefficient of the surface 131A on the pupil sideof the third lens group 103 as an aspherical surface. f denotes thefocal distance of the ocular lens in the light having a wavelength of525 nm (nanometers).

In this case, the shape coefficient sf₂ of the second lens group 102 isequal to 1.143 and satisfies the relational expression (6).

FIG. 22 shows an optical path diagram which is drawn when the pupilexists on the optical axis in the case where each parameter of theocular lens is set as shown in the equations (9). A sphericalaberration, an astigmatism, and a distortion aberration in this case areas shown in FIG. 24 and the lateral aberrations on the image surface areas shown in FIG. 25.

In FIG. 24, as for the spherical aberration, the spherical aberrationsof three kinds of light whose wavelengths are equal to 615 nm, 525 nm,and 470 nm are shown (therefore, by seeing the spherical aberration withrespect to the light of each wavelength, it expresses the verticalchromatic aberration). FIG. 25 also shows the lateral aberrations withrespect to three kinds of light whose wavelengths are equal to 615 nm,525 nm, and 470 nm. In FIG. 25, the lateral aberration in only themeridional direction is shown. In FIG. 25, further, although fivelateral aberrations of FIGS. 25A to 25E are shown, they are the lateralaberrations at the points A to E in FIG. 22. An observation angle ofvisibility as a diagonal angle is set to 40.8° (±20.4°). The points A toE in FIG. 22 are the points corresponding to the angles of visibility of20.4°, 14.3°, 0° (on the optical axis), −14.3°, and −20.4°,respectively. Since the pupil diameter is generally equal to about 2 to7 mm or about 3 to 8 mm, it is set to 4 mm as an almost intermediatevalue of them here.

The above point shall also similarly apply to spherical aberrations,astigmatisms, distortion aberrations, and lateral aberrations, whichwill be explained hereinlater.

FIG. 26 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (9).Further, FIG. 27 shows lateral aberrations on the image surface in thiscase.

Subsequently, in the case where the coefficient k₃₁ is set to −1.3 as alower limit value in the range shown in the relational expression (7),if each parameter of the ocular lens in FIG. 22 is set so that the shapecoefficient sf₂ of the second lens group 102 satisfies the relationalexpression (6), for example, they are as follows.

r0=∞d0=35.000000

r1=44.98305 d1=21.788580 nd1=1.551875 νd1=64.4815

r2=−40.62049 d2=3.000000 nd2=1.751778 νd2=31.0426

r3=−525.70221 d3=7.145805

r4=36.37975 d4=16.861732 nd4=1.530210 νd4=66.1883

r5=−260.49181 d5=9.028761

r6=56.89054 d6=4.448242 nd6=1.487000 νd6=70.4000

r7=−105.10564 d7=5.392555

r8=−32.15009 d8=4.186553 nd8=1.755000 νd8=27.6000

r9=64.84861

 a ₃₁=−0.224076×10⁻⁴

b ₃₁=0.101992×10⁻⁷

f=46.112  (10)

In this case, the shape coefficient sf₂ of the second lens group 102 isequal to 0.755 and satisfies the relational expression (6).

In the case where each parameter of the ocular lens is set as shown inthe equations (10), when the pupil exists on the optical axis, aspherical aberration, an astigmatism, and a distortion aberration are asshown in FIG. 28. Lateral aberrations on the image surface are as shownin FIG. 29.

FIG. 30 shows lateral aberrations on the image surface when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (10).

Subsequently, in the case where the coefficient k₃₁ is set to 0.6 as anupper limit value in the range shown in the relational expression (7),if each parameter of the ocular lens in FIG. 22 is set so that the shapecoefficient sf₂ of the second lens group 102 satisfies the relationalexpression (6), for example, they are as follows.

r0=∞d0=35.000000

r1=50.05161 d1=19.201337 nd1=1.556786 νd1=64.1245

r2=−42.93164 d2=3.000000 nd2=1.750946 νd2=32.0814

 r3=3414.53698 r3=0.100000

r4=38.22049 r4=20.261766 nr4=1.487000 νr4=70.4000

r5=−836.90401 r5=13.906944

r6=29.70857 r6=6.730841 nr6=1.591505 νr6=61.8656

r7=183.26213 r7=6.224333

r8=−30.65892 r8=3.00000 nr8=1.755000 νr8=27.6000

r9=91.55184

a ₃₁=0.220299×10⁻⁵

b ₃₁=−0.245065×10⁻⁷

f=46.112  (11)

In this case, the shape coefficient sf₂ of the second lens group 102 isequal to 0.913 and satisfies the relational expression (6).

In the case where each parameter of the ocular lens is set as shown inthe equations (11), when the pupil exists on the optical axis, aspherical aberration, an astigmatism, and a distortion aberration are asshown in FIG. 31. Lateral aberrations on the image surface are as shownin FIG. 32.

FIG. 33 shows lateral aberrations on the image surface when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (11).

Subsequently, FIG. 34 shows a constructional example of the secondembodiment of the ocular lens which is used as lenses 13L and 13Rconstructing the enlargement optical systems. In the diagram, portionscorresponding to those in case of FIG. 22 are designated by the samereference numerals. That is, the ocular lens is constructedfundamentally in a manner similar to the case of FIG. 22.

Even in the second embodiment, therefore, the ocular lens is constructedby the (5 elements in 4 groups) lens. That is, the ocular lens isconstructed by sequentially arranging the first lens group 101, secondlens group 102, third lens group 103, and fourth lens group 104 inaccordance with this order from the pupil side. The first lens group 101is constructed by joining the lens 111 as a positive lens and the lens112 as a negative lens. The second lens group 102 is constructed by thelens 121 as a positive lens. Further, to prevent the deterioration ofthe resolution, the shape coefficient sf₂ of the second lens group 102is also set to a value such as to satisfy the relational expression (6),namely, a value larger than 0.5.

The third lens group 103 is constructed by the lens 131 as a positivelens. The fourth lens group 104 is constructed by the lens 141 as anegative lens.

In the second embodiment, however, among the above first to fourth lensgroups 101 to 104, only the surface 131B on the screen side of the lens131 constructing the third lens group 103 is an aspherical surface.Further, in this case, now assuming that the quartic asphericalcoefficient of the surface 131B on the screen side of the third lensgroup 103 is set to a₃₂ and a predetermined coefficient is set to k₃₂,respectively, the coefficient k₃₂ is set so as to satisfy the followingrelational expression.

−0.9<k ₃₂<1.4 where, a ₃₂=(k ₃₂ /f)³  (12)

This is because when the coefficient k₃₂ is equal to or less than −0.9,an image surface in the peripheral portion of the picture plane of thevideo image is excessively bent in the negative direction and theresolution deteriorates. On the other hand, this is because when thecoefficient k₃₂ is equal to or larger than 1.4, the image surface in theperipheral portion of the picture plane of the video image isexcessively bent in the positive direction and the resolution alsodeteriorates when the pupil is moved.

Subsequently, in the case where the coefficient k₃₂ is set to, forexample, 1.000 as a value in the intermediate range of the range shownin the relational expression (12), if each parameter of the ocular lensin FIG. 34 is set so that the shape coefficient sf₂ of the second lensgroup 102 satisfies the relational expression (6), for example, they areas follows.

r0=∞d0=35.000000

r1=49.57582 d1=18.673001 nd1=1.573581 υd1=62.9774

r2=−45.49569 d2=3.000000 nd2=1.751542 υd2=31.3301

r3=239.93171 d3=0.100000

r4=43.29904 d4=10.852289 nd4=1.598668 υd4=61.4503

r5=192.70107 d5=17.389232

r6=34.67545 d6=9.794774 nd6=1.620000 υd6=60.3000

r7=−197.44785 d7=9.494566

r8=−32.76053 d8=3.000000 nd8=1.755000 υd8=27.6000

r9=82.51277

a ₃₂=0.101990×10⁻⁴

b ₃₂=−0.956666×10⁻⁸

f=46.121  (13)

where, b₃₂ denotes a sextic aspherical coefficient of the surface 131Bon the screen side of the third lens group 103 as an aspherical surface.

In this case, the shape coefficient sf₂ of the second lens group 102 isequal to 1.580 and satisfies the relational expression (6).

In the case where each parameter of the ocular lens is set as shown inthe equations (13), when the pupil exists on the optical axis, anoptical path diagram as shown in FIG. 34 is drawn. In this case, aspherical aberration, an astigmatism, and a distortion aberration are asshown in FIG. 35. Lateral aberrations on the image surface are as shownin FIG. 36.

FIG. 37 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (13).Further, FIG. 38 shows lateral aberrations on the image surface in thiscase.

Subsequently, in the case where the coefficient k₃₂ is set to −0.9 as alower limit value in the range shown in the relational expression (12),if each parameter of the ocular lens in FIG. 34 is set so that the shapecoefficient sf₂ of the second lens group 102 satisfies the relationalexpression (6), for example, they are as follows.

r0=∞d0=35.000000

r1=47.66856 d1=21.334572 nd1=1.555536 υd1=64.2144

r2=−43.66090 d2=3.000000 nd2=1.751888 υd2=30.9106

r3=7046.41554 d3=0.100000

r4=35.63434 d4=25.000000 nd4=1.487000 υd4=70.4000

r5=−881.17596 d5=7.125332

r6=27.02964 d6=5.467799 nd6=1.487000 υd6=70.4000

r7=60.81379 d7=8.495934

r8=−25.69600 d8=3.000000 nd8=1.755000 υd8=27.6000

r9=300.82749

a ₃₂=−0.743508×10⁻⁵

b ₃₂=0.677046×10⁻⁷

f=46.112  (14)

In this case, the shape coefficient sf₂ of the second lens group 102 isequal to 0.922 and satisfies the relational expression (6).

In the case where each parameter of the ocular lens is set as shown inthe equations (14), when the pupil exists on the optical axis, aspherical aberration, an astigmatism, and a distortion aberration are asshown in FIG. 39. Lateral aberrations on the image surface are as shownin FIG. 40.

FIG. 41 shows lateral aberrations on the image surface when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (14).

Subsequently, in the case where the coefficient k₃₂ is set to 1.4 as anupper limit value in the range shown in the relational expression (12),if each parameter of the ocular lens in FIG. 34 is set so that the shapecoefficient sf₂ of the second lens group 102 satisfies the relationalexpression (6), for example, they are as follows.

a ₃₂=0.279861×10⁻⁴

b ₃₂=−0.339646×10⁻⁷

f=46.112

r0=∞d0=35.000000

r1=50.34425 d1=16.590908 nd1=1.590853 υd1=61.9042

r2=−55.68133 d2=3.000000 nd2=1.752327 υd2=30.3944

r3=224.40520 d3=0.100000

r4=41.99334 d4=8.854807 nd4=1.620000 υd4=60.3000

r5=101.12743 d5=21.032002

r6=27.60385 d6=13.502596 nd6=1.533368 υd6=65.9251

r7=−65.96967 d7=5.164372

r8=−39.17709 d8=3.000000 nd8=1.755000 υd8=27.6000

r9=51.70521  (15)

In this case, the shape coefficient sf₂ of the second lens group 102 isequal to 2.420 and satisfies the relational expression (6).

In the case where each parameter of the ocular lens is set as shown inthe equations (15), when the pupil exists on the optical axis, aspherical aberration, an astigmatism, and a distortion aberration are asshown in FIG. 42. Lateral aberrations on the image surface are as shownin FIG. 43.

FIG. 45 shows a constructional example of the third embodiment of anocular lens which is used as lenses 13L and 13R constructing theenlargement optical systems. In the diagram, portions corresponding tothose in case of FIG. 22 are designated by the same reference numerals.That is, the ocular lens is constructed fundamentally in a mannersimilar to the case of FIG. 22.

Even in the third embodiment, therefore, the ocular lens is constructedby the (5 elements in 4 groups) lens. That is, the ocular lens isconstructed by sequentially arranging the first lens group 101, secondlens group 102, third lens group 103, and fourth lens group 104 inaccordance with this order from the pupil side. The first lens group 101is constructed by joining the lens 111 as a positive lens and the lens112 as a negative lens. The second lens group 102 is constructed by thelens 121 as a positive lens. Further, to prevent the deterioration ofthe resolution, the shape coefficient sf₂ of the second lens group 102is also set to a value such as to satisfy the relational expression (6),namely, a value larger than 0.5.

The third lens group 103 is constructed by the lens 131 as a positivelens. The fourth lens group 104 is constructed by the lens 141 as anegative lens.

In the third embodiment, however, among the above first to fourth lensgroups 101 to 104, only the surface 141A on the pupil side of the lens141 constructing the fourth lens group 104 is an aspherical surface.Further, in this case, now assuming that the quartic asphericalcoefficient of the surface 141A on the pupil side of the fourth lensgroup 104 is set to a₄₁ and a predetermined coefficient is set to k₄₁,respectively, the coefficient k₄₁ is set so as to satisfy the followingrelational expression.

−1.9<k ₄₁<−1.1 where, a ₄₁=(k ₄₁ /f)³  (16)

This is because when the coefficient k₄₁ is equal to or less than −1.9,an image surface in the hatched intermediate region shown in FIG. 23 isexcessively bent in the negative direction and the resolutiondeteriorates. On the other hand, this is because when the coefficientk₄₁ is equal to or larger than −1.1, the image surface in the peripheralportion of the picture plane of the video image falls down in thepositive direction and the resolution deteriorates when the pupil ismoved.

Subsequently, in the case where the coefficient k₄₁ is set to, forexample, −1.500 as a value in the intermediate range of the range shownin the relational expression (16), if each parameter of the ocular lensin FIG. 45 is set so that the shape coefficient sf₂ of the second lensgroup 102 satisfies the relational expression (6), for example, they areas follows.

r0=∞d0=35.000000

r1=46.95438 d1=15.243933 nd1=1.624863 υd1=59.3331

r2=−81.59796 d2=3.000000 nd2=1.755000 υd2=27.6000

r3=262.88850 d3=0.100000

r4=35.32537 d4=5.265233 nd4=1.634506 υd4=57.5452

r5=42.57455 d5=18.825720

r6=29.86996 d6=13.203455 nd6=1.543031 υd6=65.1511

r7=−118.63999 d7=2.892257

r8=−251.38234 d8=11.893973 nd8=1.755000 υd8=27.6000

r9=40.33824

a ₄₁=−0.344216×10⁻⁴

b ₄₁=0.373255×10⁻⁷

f=46.112  (17)

where, b₄₁ denotes a sextic aspherical coefficient of the surface 141Aon the pupil side of the fourth lens group 104 as an aspherical surface.

In this case, the shape coefficient sf₂ of the second lens group 102 isequal to 10.746 and satisfies the relational expression (6).

In the case where each parameter of the ocular lens is set as shown inthe equations (17), when the pupil exists on the optical axis, anoptical path diagram as shown in FIG. 45 is drawn. In this case, aspherical aberration, an astigmatism, and a distortion aberration are asshown in FIG. 46. Lateral aberrations on the image surface are as shownin FIG. 47.

FIG. 48 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (17).Further, FIG. 49 shows lateral aberrations on the image surface in thiscase.

Subsequently, in the case where the coefficient k₄₁ is set to −1.9 as alower limit value in the range shown in the relational expression (16),if each parameter of the ocular lens in FIG. 45 is set so that the shapecoefficient sf₂ of the second lens group 102 satisfies the relationalexpression (6), for example, they are as follows.

r0=∞d0=35.000000

r1=51.43608 d1=20.175768 nd=1.620000 υd1=60.3000

r2=−48.86497 d2=3.000000 nd2=1.755000 υd2=27.6000

r3=2852.31240 d3=0.100000

r4=29.02626 d4=6.819791 nd4=1.563701 υd4=63.6389

r5=31.02646 d5=14.886732

r6=29.14243 d6=11.868992 nd6=1.620000 υd6=60.3000

r7=293.64092 d7=8.338791

r8=−266.79528 d8=5.960953 nd8=1.664663 υd8=32.4763

r9=51.30455

a ₄₁=−0.699328×10⁻⁴

b ₄₁=0.953879×10⁻⁷

f=46.114  (18)

In this case, the shape coefficient sf₂ of the second lens group 102 isequal to 30.023 and satisfies the relational expression (6).

In the case where each parameter of the ocular lens is set as shown inthe equations (18), when the pupil exists on the optical axis, aspherical aberration, an astigmatism, and a distortion aberration are asshown in FIG. 50. Lateral aberrations on the image surface are as shownin FIG. 51.

FIG. 52 shows lateral differences on the image surface when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (18).

Subsequently, in the case where the coefficient k₄₁ is set to −1.1 as anupper limit value in the range shown in the relational expression (16),if each parameter of the ocular lens in FIG. 45 is set so that the shapecoefficient sf₂ of the second lens group 102 satisfies the relationalexpression (6), for example, they are as follows.

r0=∞d0=35.000000

r1=42.73929 d1=16.486633 nd1=1.653513 υd1=54.4529

r2=−90.08130 d2=3.000000 nd2=1.755000 υd2=27.6000

r3=102.53971 d3=0.100000

r4=44.79904 d4=6.635084 nd4=1.620000 υd4=60.3000

r5=90.04515 d5=16.723563

r6=34.62602 d6=7.621149 nd6=1.487000 υd6=70.4000

r7=180.67253 d7=1.334160

r8=74.08869 d8=17.786101 nd8=1.755000 υd8=27.6000

r9=34.28271

a ₄₁=−0.135749×10⁻⁴

b ₄₁=−0.106893×10⁻⁷

f=46.112  (19)

In this case, the shape coefficient sf₂ of the second lens group 102 isequal to 2.980 and satisfies the relational expression (6).

In the case where each parameter of the ocular lens is set as shown inthe equations (19), when the pupil exists on the optical axis, aspherical aberration, an astigmatism, and a distortion aberration are asshown in FIG. 53. Lateral aberrations on the image surface are as shownin FIG. 54.

FIG. 55 shows lateral differences on the image surface when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (19).

Subsequently, FIG. 56 shows a constructional example of the fourthembodiment of an ocular lens which is used as lenses 13L and 13Rconstructing the enlargement optical systems. In the diagram, portionscorresponding to those in case of FIG. 22 are designated by the samereference numerals. That is, the ocular lens is constructedfundamentally in a manner similar to the case of FIG. 22.

Even in the fourth embodiment, therefore, the ocular lens is constructedby the (5 elements in 4 groups) lens. That is, the ocular lens isconstructed by sequentially arranging the first lens group 101, secondlens group 102, third lens group 103, and fourth lens group 104 inaccordance with this order from the pupil side. The first lens group 101is constructed by joining the lens 111 as a positive lens and the lens112 as a negative lens. The second lens group 102 is constructed by thelens 121 as a positive lens. Further, to prevent the deterioration ofthe resolution, the shape coefficient sf₂ of the second lens group 102is set to a value such as to satisfy the relational expression (6),namely, a value larger than 0.5.

The third lens group 103 is constructed by the lens 131 as a positivelens. The fourth lens group 104 is constructed by the lens 141 as anegative lens.

In the fourth embodiment, however, among the above first to fourth lensgroups 101 to 104, only the surface 141B on the screen side of the lens141 constructing the fourth lens group 104 is an aspherical surface.Further, in this case, now assuming that the quartic asphericalcoefficient of the surface 141B on the screen side of the fourth lensgroup 104 is set to a₄₂ and a predetermined coefficient is set to k₄₂,respectively, the coefficient k₄₂ is set so as to satisfy the followingrelational expression.

−1.8<k ₄₂<2.0 where, a ₄₂=(k ₄₂ /f)³  (20)

This is because if the coefficient k₄₂ is equal to or less than −1.8, acoma aberration increases in the peripheral portion of the picture planeof the video image when the pupil is moved and the resolutiondeteriorates. Further, in this case, this is because the distortionaberration also increases in the negative direction. On the other hand,this is also because when the coefficient k₄₂ is equal to or larger than2.0, an image surface is excessively bent in the negative direction inthe hatched intermediate region shown in FIG. 23, the image surface isexcessively bent in the positive direction in the peripheral portion,and the resolution deteriorates. Further, this is because the distortionaberration also increases in the positive direction.

Subsequently, in the case where the coefficient k₄₂ is set to 1.700 as avalue in the intermediate range of the range shown in the relationalexpression (20), if each parameter of the ocular lens in FIG. 56 is setso that the shape coefficient sf₂ of the second lens group 102 satisfiesthe relational expression (6), for example, they are as follows.

r0=∞d0=35.000000

r1=57.33885 d1=18.369087 nd1=1.627197 υd1=53.4628

r2=−39.79919 d2=3.000000 nd2=1.752596 υd2=30.0865

r3=370.26370 d3=0.100000

r4=37.88815 d4=14.933140 nd4=1.487000 υd4=70.4000

r5=632.70628 d5=19.132328

r6=27.34086 d6=7.538561 nd6=1.620000 υd6=60.3000

r7=87.43207 d7=7.581556

r8=−29.49375 d8=3.000000 nd8=1.755000 υd8=27.6000

r9=327.65071

a ₄₂=0.501077×10⁻⁴

b ₄₂=−0.173207×10⁶

f=46.112  (21)

where, b₄₂ denotes a sextic aspherical coefficient of the surface 141Bon the screen side of the fourth lens group 104 as an asphericalsurface.

In this case, the shape coefficient sf₂ of the second lens group 102 isequal to 1.127 and satisfies the relational expression (6).

In the case where each parameter of the ocular lens is set as shown inthe equations (21), when the pupil exists on the optical axis, anoptical path diagram as shown in FIG. 56 is drawn. In this case, aspherical aberration, an astigmatism, and a distortion aberration are asshown in FIG. 57. Lateral aberrations on the image surface are as shownin FIG. 58.

FIG. 59 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (21).Further, FIG. 60 shows lateral aberrations on the image surface in thiscase.

Subsequently, in the case where the coefficient k₄₂ is set to −1.8 as alower limit value in the range shown in the relational expression (20),if each parameter of the ocular lens in FIG. 56 is set so that the shapecoefficient sf₂ of the second lens group 102 satisfies the relationalexpression (6), for example, they are as follows.

r0=∞d0=35.000000

r1=63.74873 d1=16.817964 nd1=1.648512 υd1=49.6557

r2=−41.34616 d2=3.000000 nd2=1.755000 υd2=27.6000

r3=540.21774 d3=0.100000

r4=37.57345 d4=13.547257 nd4=1.487000 υd4=70.4000

r5=209.85729 d5=21.708479

r6=26.83056 d6=8.662030 nd6=1.620000 υd6=60.3000

r7=130.40070 d7=7.164270

r8=−30.19076 d8=3.000000 nd8=1.755000 υd8=27.6000

r9=32.73832

a ₄₂=−0.594804×10⁻⁴

b ₄₂=−0.600080×10⁻⁸

f=46.112  (22)

In this case, the shape coefficient sf₂ of the second lens group 102 isequal to 1.436 and satisfies the relational expression (6).

In the case where each parameter of the ocular lens is set as shown inthe equations (22), when the pupil exists on the optical axis, aspherical aberration, an astigmatism, and a distortion aberration are asshown in FIG. 61. Lateral aberrations on the image surface are as shownin FIG. 62.

FIG. 63 shows lateral aberrations on the image surface when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (22).Subsequently, in the case where the coefficient k₄₂ is set to 2.0 as anupper limit value in the range shown in the relational expression (20),if each parameter of the ocular lens in FIG. 56 is set so that the shapecoefficient sf₂ of the second lens group 102 satisfies the relationalexpression (6), for example, they are as follows.

r0=∞d0=35.000000

r1=57.12941 d1=16.680182 nd1=1.614935 υd1=54.1070

r2=−46.27543 d2=3.000000 nd2=1.753322 υd2=29.2884

r3=308.46978 d3=0.100000

r4=38.05458 d4=13.868119 nd4=1.487000 υd4=70.4000

r5=293.50877 d5=20.101568

r6=28.03696 d6=8.406043 nd6=1.675762 υd6=51.4159

r7=125.69552 d7=6.342776

r8=−36.16103 d8=3.000000 nd8=1.755000 υd8=27.6000

r9=29279.63461

a ₄₂=0.815921×10⁻⁴

b ₄₂=−0.213534×10⁻⁶

f=46.112  (23)

In this case, the shape coefficient sf₂ of the second lens group 102 isequal to 1.298 and satisfies the relational expression (6).

In the case where each parameter of the ocular lens is set as shown inthe equations (23), when the pupil exists on the optical axis, aspherical aberration, an astigmatism, and a distortion aberration are asshown in FIG. 64. Lateral aberrations on the image surface are as shownin FIG. 65.

FIG. 66 shows lateral aberrations on the image surface when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (23).

According to the construction as described above, high resolution and along eye relief are obtained over angles of view of 40° or more as adiagonal angle, and the ocular lens which has high resolution even ifthe pupil position is slightly deviated from the optical axis can beprovided.

As will be obviously understood from the equations (9) to (11), (13) to(15), (17) to (19), and (21) to (23), a value of 0.75f or more isassured as an eye relief.

The display apparatus 7 for forming a virtual image of a video image bythe ocular lens described above and providing will now be described.

FIG. 67 shows a ninth constructional example of the display apparatus 7.

A display element (image display element) 151 is a display device of aself light emitting type or transmitting type (self light emitting typedevice or transmitting light control type device) and displays a videoimage to be provided for the user.

That is, the display element 151 is a display device constructed asdescribed in FIGS. 6 or 7. The video image displayed there is projectedonto a translucent screen 153 through a projecting lens 152. The videoimage projected onto the translucent screen 153 passes through an ocularlens 154 constructed as shown in FIGS. 22, 34, 45, or 56, so that itenters the eyeballs of the user. Thus, a virtual image of the videoimage displayed on the display element 151 is observed in the eyeballsof the user.

In the above construction, the projecting lens 152, translucent screen153, and ocular lens 154 construct an enlargement optical system.

FIG. 68 shows a tenth constructional example of the display apparatus 7.In the diagram, portions corresponding to those in case of FIG. 67 aredesignated by the same reference numerals. That is, the displayapparatus 7 is constructed in a manner similar to the case of FIG. 67except that the translucent screen 153 is not provided.

In the display apparatus 7 in FIG. 68, a video image displayed on thedisplay element 151 passes through the projecting lens 152, so that anaerial image 161 of the video image is formed at a position where, forexample, the translucent screen 153 is installed in FIG. 67. The aerialimage 161 passes through the ocular lens 154 and enters the eyeballs ofthe user, so that the virtual image of the video image displayed in thedisplay element 151 is observed by the eyeballs of the user. In thiscase, as shown by an alternate long and short dash line in FIG. 68, afield lens 155 can be arranged near the aerial image 161. In this case,a peripheral light amount of the image seen through the ocular lens 154can be increased.

FIG. 69 shows an eleventh constructional example of the displayapparatus 7. In the diagram, portions corresponding to those in the caseof FIG. 67 are designated by the same reference numerals. That is, thedisplay apparatus 7 is constructed in a manner similar to the case ofFIG. 67 except that the projecting lens 152 and translucent screen 153are not provided.

In the display apparatus 7, since the video image displayed on thedisplay element 151 directly passes through the ocular lens 154, itenters the eyeballs of the user, so that the virtual image of the videoimage displayed in the display element 151 is observed by the eyeballsof the user.

When the display region of the display element 151 is large, as shown inFIG. 69, merely by seeing the video image displayed by the displayelement 151 through only the ocular lens 154 without enlarging by theprojecting lens 152, the angle of view can be widened and the eye reliefcan be made long. When the display region of the display element 151 issmall, if the focal distance of the ocular lens 154 is short, althoughthe angle of view is widened, the eye relief becomes short. On the otherhand, when the focal distance of the ocular lens 154 is long, althoughthe eye relief is long, the angle of view is narrowed. When the displayregion of the display element 151 is small, therefore, as shown in FIG.67, it is sufficient that the video image on the display element 151 isenlarged onto the translucent screen 153 by the projecting lens 152 andthe enlarged video image is seen through the ocular lens 154. In thiscase, the angle of view can be widened and the eye relief can be madelong.

FIG. 70 shows a twelfth constructional example of the display apparatus7. In the diagram, portions corresponding to those in the case of FIG.67 are designated by the same reference numerals. That is, the displayapparatus 7 is constructed in a manner similar to the case of FIG. 67except that a display element 171 and a PBS (polarization beam splitter)172 are provided in place of the display element 151.

Light as illumination light emitted from a light source (not shown) isreflected by 90° in the PBS 172 and enters the display element (imagedisplay element) 171. As described in FIG. 8, in the display element171, the light entering there is reflected by a reflecting type displaydevice (reflecting light control type device), thereby displaying avideo image to be provided to the user.

The video image as reflection light in the display element 171 transmitsthe PBS 172 and enters the projecting lens 152. A virtual image issubsequently observed by the eyeballs of the user in a manner similar tothe case of FIG. 67.

In FIG. 70 as well, since the video image displayed on the displayelement 171 is enlarged by the projecting lens 152, even if a displayregion of the display element 171 is small, the angle of view can bewidened and the eye relief can be made long.

A half mirror or another device for dividing the light can be alsoprovided in place of the PBS 172.

FIG. 71 shows a thirteenth constructional example of the displayapparatus 7. In the diagram, portions corresponding to those in the caseof FIGS. 68 or 70 are designated by the same reference numerals. Thatis, the display apparatus 7 is constructed in a manner similar to thecase of FIG. 68 except that the display element 171 and PBS 172 areprovided in place of the display element 151.

In the display apparatus 7, light as illumination light emitted from alight source (not shown) is reflected by 90° by the PBS 172 and entersthe display element 171. In the display element 171, the light enteringthere is reflected and a video image as reflection light transmits thePBS 172 and enters the projecting lens 152. In a manner similar to thecase of FIG. 68, subsequently, a virtual image is observed in theeyeballs of the user. In this case as well, by arranging the field lens155, a peripheral light amount of the image can be increased in a mannersimilar to the case of FIG. 47.

FIG. 72 shows a fourteenth constructional example of the displayapparatus 7. In the diagram, portions corresponding to those in the caseof FIG. 70 are designated by the same reference numerals. That is, thedisplay apparatus 7 is constructed in a manner similar to the case ofFIG. 70 except that the PBS 172 is provided between the projecting lens152 and ocular lens 154 instead of a position between the displayelement 151 and projecting lens 152.

In this case, light as illumination light emitted from a light source(not shown) is reflected by 90° in the PBS 172 and enters the displayelement 171 through the projecting lens 152. In the display element 171,the light entering there is reflected and a video image as a reflectionlight transmits the projecting lens 152 and PBS 172 and is enlargedlyprojected onto the translucent screen 153. In a manner similar to thecase of FIG. 70, subsequently, a virtual image is observed in theeyeballs of the user.

By a similar principle, in FIG. 71, the PBS 172 can be also providedbetween the projecting lens 152 and ocular lens 154 instead of aposition between the display element 151 and projecting lens 152.

FIG. 73 shows a fifteenth constructional example of the displayapparatus 7. In the diagram, portions corresponding to those in the caseof FIG. 67 are designated by the same reference numerals.

In this case, light as a video image displayed in the display element151 enters a mirror 182 through the projecting lens 152. In the mirror182, the light from the projecting lens 152 is reflected by 90° and isemitted to a mirror 181. In the mirror 181, a reflection light from themirror 182 is further reflected by 90° and the reflected light isprojected onto the translucent screen 153. The video image projected onthe translucent screen 153 passes through the ocular lens 154 and entersthe eyeballs of the user. Thus, a virtual image of the video imagedisplayed in the display element 151 is observed by the eyeballs of theuser.

FIG. 74 shows a sixteenth constructional example of the displayapparatus 7. In the diagram, portions corresponding to those in the caseof FIGS. 70 or 73 are designated by the same reference numerals.

In this case, light as illumination light emitted from a light source(not shown) is reflected by 90° in the PBS 172. In the display element171, the light entering there is reflected, thereby forming a videoimage to be provided to the user. A reflection light as a video imagetransmits the PBS 172 and projecting lens 152 and enters the mirror 182.In a manner similar to the case of FIG. 73, subsequently, a virtualimage is observed in the eyeballs of the user.

That is, in FIGS. 67 to 51, the display element 151 or 171, projectinglens 152, and ocular lens 154 have been arranged in a straight line.However, as shown in FIGS. 73 or 74, the display apparatus 7 can be alsoconstructed so as to bend the optical path by inserting the mirrors 181and 182 in the halfway. In this case, the apparatus can be miniaturized.

FIG. 75 shows a seventeenth constructional example of the displayapparatus 7.

In light emitting diodes 191R, 191G, and 191B, light of red, green, andblue is emitted as illumination light, respectively. The light enters aPBS 195 through a dichroic prism 192, a fly eye lens 193, and a fieldlens 194, respectively. In the PBS 195, the light from the field lens194 is reflected by 90° and its reflected light enters a reflecting typevideo display panel 196 as a reflecting type display device. In thereflecting type video display panel 196, by reflecting the lightentering there, a video image to be provided to the user is formed. Thereflected light as a video image is enlargedly projected to atranslucent screen 198 through the PBS 195 and a projecting lens 197.The enlarged and projected image enters the eyeballs of the user throughan ocular lens 199 constructed as shown in FIGS. 22, 34, 45, or 56.Thus, a virtual image of the video image displayed on the reflectingtype video display panel 196 is observed by the eyeballs of the user.

In this case, since the light of red, green, and blue is irradiated asillumination light to the reflecting type video display panel 196, acolor virtual image can be provided by what is called a field sequentialsystem.

FIG. 76 shows an eighteenth constructional example of the displayapparatus 7. In the diagram, portions corresponding to those in the caseof FIG. 75 are designated by the same reference numerals. That is, thedisplay apparatus 7 is constructed in a manner similar to the case ofFIG. 75 except that a mirror 201 is provided between the fly eye lens193 and field lens 194, mirrors 202 and 203 are provided between theprojecting lens 197 and translucent screen 198, and further, a wholeapparatus is fixed in a casing 204.

In the embodiment, light as illumination light from the fly eye lens 193is reflected by 90° by the mirror 201 and enters the PBS 195 through thefield lens 194. In the PBS 195, the light from the field lens 194 isreflected by 90° and its reflected light enters the reflecting typevideo display panel 196. In the reflecting type video display panel 196,the light entering there is reflected by 180°, thereby forming a videoimage to be provided to the user. The reflected light as a video imageenters the mirror 202 through the PBS 195 and projecting lens 197. Inthe mirror 202, the light from the projecting lens 197 is reflected by90° and its reflected light enters the mirror 203. In the mirror 203,the reflected light from the mirror 202 is further reflected by 90°.Thus, the image enlarged by the projecting lens 197 is projected ontothe translucent screen 198. In a manner similar to the case of FIG. 75,a virtual image of the video image displayed on the reflecting typevideo display panel 196 is observed by the eyeballs of the user.

As mentioned above, by bending the optical path by the mirrors 201 to203, the apparatus can be miniaturized.

FIG. 77 shows a nineteenth constructional example of the displayapparatus 7.

In the embodiment, two sets of display apparatuses 7 shown in FIG. 76are provided, thereby enabling virtual images which are formed to beobserved by the left eye and right eye, respectively.

That is, in FIG. 77, light emitting diodes 191RL, 191GL, and 191BL, adichroic prism 192L, a fly eye lens 193L, a field lens 194L, a PBS 195L,a reflecting type video display panel 196L, a projecting lens 197L, atranslucent screen 198L, an ocular lens 199L, and mirrors 201L to 203Lare constructed in a manner similar to the light emitting diodes 191R,191G, and 191B, dichroic prism 192, fly eye lens 193, field lens 194,PBS 195, reflecting type video display panel 196, projecting lens 197,translucent screen 198, ocular lens 199, and mirrors 201 to 203 in FIG.76, respectively, thereby enabling a virtual image to be provided to theleft eye of the user. In FIG. 77, light emitting diodes 191RR, 191GR,and 191BR, a dichroic prism 192R, a fly eye lens 193R, a field lens194R, a PBS 195R, a reflecting type video display panel 196R, aprojecting lens 197R, a translucent screen 198R, an ocular lens 199R,and mirrors 201R to 203R are also constructed in a manner similar to thelight emitting diodes 191R, 191G, and 191B, dichroic prism 192, fly eyelens 193, field lens 194, PBS 195, reflecting type video display panel196, projecting lens 197, translucent screen 198, ocular lens 199, andmirrors 201 to 203 in FIG. 76, respectively, thereby enabling a virtualimage to be provided to the right eye of the user.

In this case, therefore, the user can observe the virtual images by theright and left eyes.

The arranging positions of the mirrors 201 to 203 in FIG. 76 and themirrors 201L to 203L and 201R to 203R in FIG. 77 are not limited to thepositions shown in FIGS. 76 and 77. That is, in the embodiment of FIGS.76 or 77, the mirrors are arranged so as to bend the optical path in thedirection which is parallel with the drawing. However, as anotherarrangement, for example, the mirrors can be also arranged so as to bendthe optical path in the direction perpendicular to the drawing.

As mentioned above, according to the display apparatus 7 using theocular lens constructed as shown in FIGS. 22, 34, 45, or 56, a videoimage of high resolution and a wide angle of view can be provided. Inthe case where such a display apparatus 7 is fixed to an object otherthan the user, for example, even if the pupil of the user is deviatedfrom the optical axis because of the movement of the user, a video image(virtual image) of high resolution can be provided. In the ocular lensshown in FIGS. 22, 34, 45, or 56, since the eye relief can be made long,it is also possible to cope with a case where the user moves in theoptical axial direction.

In the above case, among the first to fourth lens groups 101 to 104,only one surface of the third lens group 103 or fourth lens group 104has been formed as an aspherical surface. However, two or more surfacesof the third lens group 103 or fourth lens group 104 can be also formedso as to have aspherical surfaces. Although the surfaces of the firstlens group 101 and second lens group 102 can be formed by asphericalsurfaces, by forming the surface of the third lens group 103 or fourthlens group 104 by an aspherical surface, an astigmatism and a comaaberration can be reduced.

Further, although the quartic aspherical coefficient of the lens hasbeen limited in the above case, as another method, for example, even bylimiting the sextic aspherical coefficient of the lens, performancesimilar to that in case of limiting the quartic aspherical coefficientof the lens can be derived.

In the case where none of the surfaces in the third lens group 103 orfourth lens group 104 is formed by the aspherical surface, theastigmatism, distortion aberration, and the like increase. It isdifficult to realize the eye relief of 0.75f or more by setting thediagonal angle of view to 40° or more while keeping the resolution asmentioned above.

In the display apparatus 7, as a screen which is used in the case wherea video image is projected onto the screen by a projection opticalsystem such as a projecting lens or the like and its projector isobserved through the ocular lens, for example, there is a reflectingtype besides the translucent type shown in FIG. 67 or the like. In caseof using the reflecting type screen, it is necessary to irradiate thelight from the projection optical system to the reflecting type screenand to allow the reflection light reflected by 180° there to enter theocular lens. In this case, since the optical path from the projectionoptical system to the screen and the optical path from the screen to theocular lens overlap, in general, one of the optical paths is bent by ahalf mirror or the like, thereby making the optical path between thehalf mirror and the projection optical system and the optical pathbetween the half mirror and the ocular lens different.

In this case, since the half mirror is arranged in the optical pathbetween the ocular lens and the screen, a space for installation isneeded in such an interval. It is, therefore, necessary to set aslightly long distance as a distance between the ocular lens and thescreen. However, a request to make the distance between the ocular lensand the screen (distance on the optical axis) long and a request to makethe eye relief long are also contradictory requests.

In this case, in order to prevent an enlargement in size of the wholeapparatus by the installation of the half mirror, for instance, it isnecessary to shorten the length of ocular lens. To shorten the length ofocular lens, it is necessary to reduce the number of lenses constructingthe ocular lens. However, it is extremely difficult to realize highresolution by a small number of lenses.

Specifically speaking, in the ocular lens disclosed in, for example,U.S. Pat. No. 2,637,245 or the like, the angle of view (apparent fieldof view) is equal to about 42° and the eye relief is equal to about1.376f, so that a high eye point is obtained. However, the distancebetween the ocular lens and the screen is short to be about 0.243f.Further, it is difficult to cope with the standard of UXGA or HDTV.

FIG. 78 shows a constructional example of the fifth embodiment of anocular lens which is used as lenses 13L and 13R constructing theenlargement optical systems.

In the embodiment (the same shall also similarly apply in ocular lensesof the other embodiments, which will be explained hereinlater), the eyerelief is set to, for instance, 40 mm and an allowance amount of thedeviation of the pupil position is set to ±9 mm. Further, the angle ofview is set so that the horizontal angle of view (total angle) of 35° ormore and the diagonal angle of view (total angle) of 40° or more can beassured.

In the ocular lens of the fifth embodiment of FIG. 78 (the same shallalso similarly apply in the ocular lenses in the other embodiments,which will be explained hereinlater), a back focus (distance between theocular lens and the image which is formed on the screen or the like) isset to a value similar to the eye relief. That is, the back focus is setso that about 40 mm similar to the foregoing eye relief can be assured.

Further, the ocular lens of the fifth embodiment of FIG. 78 (the sameshall also similarly apply in the ocular lenses in the otherembodiments, which will be explained hereinlater) is constructed by a (4elements in 2 groups) lens for the purpose of miniaturization of theapparatus. In the case where the number of lenses constructing theocular lens is reduced as mentioned above, it is difficult to realizeboth of what is called an achromatism and a flatness of the imagesurface of the ocular lens. Therefore, for example, priority is given tothe achromatism here. In case of giving the priority to the achromatismas mentioned above, since a refractive index, a variance value, and thelike of the lenses which are used for constructing the ocular lens arelimited, it is difficult to flatten the image surface by reducing theimage surface curve. That is, when the priority is given to theachromatism in the ocular lens having a small number of elements, itgenerally cannot avoid that the image surface becomes a curved surface.

When the image projected onto the screen or the like by, for example, aprojection optical system with less aberration is observed by the ocularlens having a curved image surface, in a peripheral region (edgeportion) of the curved surface away from the optical axis, the imagebecomes blur and the resolution deteriorates. Therefore, it is nowassumed that in the projection optical system, an image of the curvedimage surface which coincides with the image surface of the ocular lensis formed. Thus, even in the peripheral region of the picture plane, theimage does not become blur and a video image of high resolution can beobserved. As a method of allowing the projection optical system to forman image of the curved image surface, for example, there is a methodwhereby the screen to which the projection optical system projects animage is formed in such a curved shape or the like.

If a blur of the image in the peripheral region of the picture plane ispermitted, there is no need to allow the projection optical system toform an image of the curved image surface.

In FIG. 78, the ocular lens is constructed by a (4 elements in 2 groups)lens as mentioned above. That is, the ocular lens is constructed bysequentially arranging a first lens group 301 and a second lens group302 in accordance with the order from the pupil side. In FIG. 78, ascreen to which the image formed by the projection optical system isprojected or the like is disposed on the right side of the second lensgroup 302. By seeing the image from the left side (pupil side) of thefirst lens group 301, its virtual image can be observed.

The first lens group 301 (first lens group) is constructed bysequentially joining a lens 311 as a positive lens and a lens 312 as anegative lens in accordance with the order seen from the pupil side.That is, the lens 311 is arranged on the pupil side and the lens 312 isarranged on the side (screen side) opposite to the pupil, respectively.

The second lens group 302 (second lens group) is constructed bysequentially joining a lens 321 as a negative lens and a lens 322 as apositive lens in accordance with the order seen from the pupil side.That is, the lens 321 is arranged on the pupil side and the lens 322 isarranged on the screen side, respectively.

In the foregoing first lens group 301 or second lens group 302, only asurface 311A on the pupil side of the lens 311 constructing the firstlens group 301 is formed by an aspherical surface. Further in this case,now assuming that a quartic aspherical coefficient of the surface 311Aon the pupil side of the first lens group 301 is labeled as a₁₁ and thefocal distance of the whole system of the ocular lens is set to f and apredetermined coefficient is set to k₁₁, respectively, the coefficientk₁₁ is set so as to satisfy the following relational expression.

−0.9<k ₁₁<−0.5 where, a ₁₁=(k ₁₁ /f)³  (24)

This is because if the coefficient k₁₁ is equal to −0.9 or less, whenthe pupil moves from the optical axis, the image surface of theperipheral region of the picture plane of the video image (edge portionof the picture plane) on the side opposite to the moving direction fallsdown in the negative direction and the resolution deteriorates. On theother hand, this is also because if the coefficient k₁₁ is equal to −0.5or more, when the pupil moves from the optical axis, the image surfacein the moving direction falls down in the positive direction and theresolution deteriorates. A state where the image surface is excessivelybent in the positive or negative direction denotes that a curve showingan average image surface which is derived from an astigmatism curve inthe sagittal direction (S direction) and an astigmatism curve in themeridional direction (M direction) is excessively inclined in thepositive or negative direction.

It is not limited to a situation such that the relational expression(24) (the same shall also similarly apply to the other conditionalexpressions, which will be explained hereinlater) certainly satisfiesthe condition. However, when the condition of the relational expression(24) is not satisfied, the resolution of the ocular lens deteriorates interms of the meaning as described in the first embodiment of the ocularlens.

Subsequently, in the case where only the surface 311A on the pupil sideof the lens 311 in the first lens group 301 is formed by the asphericalsurface and the coefficient k₁₁ is set to −0.7 as a value within theintermediate range of the range shown in the relational expression (24),each parameter of the ocular lens is, for instance, as shown below.

r0=∞d0=40.000000

r1=50.07380 d1=21.596783 nd1=1.540033 υd1=65.3863

r2=−45.97502 d2=16.930953 nd2=1.744445 υd2=43.5917

r3=−82.60234 d3=1.000000

r4=90.60758 d4=3.000000 nd4=1.746911 υd4=38.3455

r5=30.31965 d5=17.472265 nd5=1.487000 υd5=70.4000

r6=−7038.46034 d6=40.000000

r7=−75.00000

a ₁₁=−0.970425×10⁻⁶

b ₁₁=−0.134184×10⁻⁹

f=70.704  (25)

where, in the equations (25) and subsequent equations, r0 to r7 denotethe radii of curvature (mm) in the pupil surface, the surface on thepupil side of the lens 311, the surface on the screen side of the lens311 (surface on the pupil side of the lens 312), the surface on thepupil side of the lens 312, the surface on the pupil side of the lens321, the surface on the screen side of the lens 321 (surface on thepupil side of the lens 322), the surface on the screen side of the lens322, and the image surface of the image which is formed on the screen orthe like by the projection optical system, respectively. d0 denotes thedistance (eye relief) (mm) from the pupil to the ocular lens, namely, tothe lens 311 of the first lens group 301. d1 to d6 indicate thethickness of the lens 311, the thickness of the lens 312, the air gapbetween the lenses 312 and 321, the thickness of the lens 321, thethickness of the lens 322, and the distance (back focus) (mm) from thelens 322 to the image which is formed on the screen or the like,respectively. Further, nd1, nd2, nd4, or nd5 denotes the refractiveindex in a d line of a nitride material of each of the lenses 311, 312,321, and 322, respectively. υd1, υd2, υd4, or υd5 denotes the Abbenumber in the d line of the nitride material of each of the lens 311,312, 321, or 322, respectively. a₁₁ or b₁₁ denotes the quartic or sexticaspherical coefficient of the surface 311A on the pupil side of thefirst lens group 301 (surface on the pupil side of the lens 311) as anaspherical surface, respectively. f denotes the focal distance of theocular lens in the light having a wavelength of 525 nm (nanometers).

When each parameter of the ocular lens is set as shown by the equations(25), shapes of the lenses 311, 312, 321, and 322 are as shown in FIG.78. Further, when the pupil exists on the optical axis, an optical pathdiagram as shown in FIG. 78 is drawn. A spherical aberration, anastigmatism, and a distortion aberration in this case are as shown inFIG. 79 and lateral aberrations on the image surface are as shown inFIG. 80.

FIG. 81 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (25).Further, FIG. 82 shows lateral aberrations on the image surface in thiscase.

In optical path diagrams shown below including FIG. 78, the opticalpaths D and E among the five optical paths A to E described in the firstembodiment of the ocular lens are omitted in the diagrams.

Subsequently, in the case where only the surface 311A on the pupil sideof the lens 311 in the first lens group 301 is formed by the asphericalsurface and the coefficient k₁₁ is set to −0.9 as a lower limit valuewithin the range shown in the relational expression (24), each parameterof the ocular lens is, for instance, as shown below.

r0=∞d0=40.000000

r1=46.78293 d1=25.517040 nd1=1.487000 υd1=70.4000

r2=−36.86474 d2=11.080586 nd2=1.698553 υd2=47.7991

r3=−57.08138 d3=1.000000

r4=160.01023 d4=3.206065 nd4=1.745732 υd4=40.6829

r5=32.53695 d5=19.196310 nd5=1.487000 υd5=70.4000

r6=−251.08445 d6=39.999999

r7=−75.00000

a ₁₁=−0.206251×10⁻⁵

b ₁₁=−0.162838×10⁻⁹

f=70.704  (26)

When each parameter of the ocular lens is set as shown by the equations(26), shapes of the lenses 311, 312, 321, and 322 are as shown in FIG.83. Further, when the pupil exists on the optical axis, an optical pathdiagram as shown in FIG. 83 is drawn. A spherical aberration, anastigmatism, and a distortion aberration in this case are as shown inFIG. 84 and lateral aberrations on the image surface are as shown inFIG. 85.

FIG. 86 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (26).Further, FIG. 87 shows lateral aberrations on the image surface in thiscase.

Subsequently, in the case where only the surface 311A on the pupil sideof the lens 311 in the first lens group 301 is formed by the asphericalsurface and the coefficient k₁₁ is set to −0.5 as an upper limit valuewithin the range shown in the relational expression (24), each parameterof the ocular lens is, for instance, as shown below.

r0=∞d0=40.000000

r1=56.36241 d1=19.832046 nd1=1.610052 υd1=60.8210

r2=−48.36727 d2=18.528516 nd2=1.744406 υd2=43.6864

r3=−128.12790 d3=1.000000

r4=80.08954 d4=3.000000 nd4=1.747707 υd4=36.9175

r5=30.32276 d5=17.639439 nd5=1.487000 υd5=70.4000

r6=−812.28344 d6=40.000000

r7=−75.00000

a ₁₁=−0.353654×10⁻⁶

b ₁₁=−0.350604×10⁻¹¹

f=70.704  (27)

When each parameter of the ocular lens is set as shown by the equations(27), shapes of the lenses 311, 312, 321, and 322 are as shown in FIG.88. Further, when the pupil exists on the optical axis, an optical pathdiagram as shown in FIG. 88 is drawn. A spherical aberration, anastigmatism, and a distortion aberration in this case are as shown inFIG. 89 and lateral aberrations on the image surface are as shown inFIG. 90.

FIG. 91 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (27).Further, FIG. 92 shows lateral aberrations on the image surface in thiscase.

FIG. 93 shows a constructional example of the sixth embodiment of anocular lens which is used as lenses 13L and 13R constructing theenlargement optical system. In the diagram, portions corresponding tothose in case of FIG. 78 are designated by the same reference numerals.That is, the ocular lens is fundamentally constructed in a mannersimilar to the case of FIG. 78.

In the sixth embodiment, in the first lens group 301 or second lensgroup 302, only a surface 312B on the screen side of the lens 312constructing the first lens group 301 is formed by an asphericalsurface. In this case, further, now assuming that a quartic asphericalcoefficient of the surface 312B on the screen side of the first lensgroup 301 is labeled as a₁₂ and the focal distance of the whole systemof the ocular lens is set to f and a predetermined coefficient is set tok₁₂ respectively, the coefficient k₁₂ is set so as to satisfy thefollowing relational expression.

−0.1<k ₁₂<1.2 where, a ₁₂=(k ₁₂ /f)³  (28)

This is because if the coefficient k₁₂ is equal to −0.1 or less, theimage surface in the peripheral region of the picture plane of the videoimage is excessively bent in the positive direction and the resolutiondeteriorates. On the other hand, this is also because if the coefficientk₁₂ is equal to 1.2 or more, when the pupil moves from the optical axis,the image surface in the peripheral portion of the picture plane of thevideo image on the side opposite to the moving direction falls down inthe positive direction and the resolution deteriorates.

Subsequently, in the case where only the surface 312B on the screen sideof the lens 312 in the first lens group 301 is formed by the asphericalsurface and the coefficient k₁₂ is set to 1.1 as a value within theintermediate range of the range shown in the relational expression (28),each parameter of the ocular lens is, for instance, as shown below.

r0=∞d0=40.000000

r1=47.90263 d1=20.532074 nd1=1.549677 υd1=64.6446

r2=−61.94314 d2=4.449320 nd2=1.487000 υd2=70.4000

r3=−142.84458 d3=4.095881

r4=−280.44421 d4=3.000000 nd4=1.748102 υd4=36.2474

r5=41.59350 d5=27.922724 nd5=1.487000 υd5=70.4000

r6=−49.29290 d6=40.000000

r7=−75.00000

a ₁₂=0.376570×10⁻⁵

b ₁₂=0.403927×10⁻⁹

f=70.704  (29)

where, b₁₂ denotes a sextic aspherical coefficient of the surface 312Bon the screen side of the lens 312 of the first lens group 301 as anaspherical surface.

When each parameter of the ocular lens is set as shown by the equations(29), shapes of the lenses 311, 312, 321, and 322 are as shown in FIG.93. Further, when the pupil exists on the optical axis, an optical pathdiagram as shown in FIG. 93 is drawn. A spherical aberration, anastigmatism, and a distortion aberration in this case are as shown inFIG. 94 and lateral aberrations on the image surface are as shown inFIG. 95.

FIG. 96 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (29).Further, FIG. 97 shows lateral aberrations on the image surface in thiscase.

Subsequently, in the case where only the surface 312B on the screen sideof the lens 312 in the first lens group 301 is formed by the asphericalsurface and the coefficient k₁₂ is set to −0.1 as a lower limit valuewithin the range shown in the relational expression (28), each parameterof the ocular lens is, for instance, as shown below.

r0=∞d0=40.000000

r1=59.60024 d1=22.208164 nd1=1.561732 υd1=61.3018

r2=−39.79904 d2=9.621365 nd2=1.744000 υd2=44.7000

r3=−110.13093 d3=1.000000

r4=73.87884 d4=8.203051 nd4=1.747301 υd4=37.6311

r5=30.04885 d5=18.967420 nd5=1.487000 υd5=70.4000

r6=−266.58052 d6=40.000000

r7=−75.00000

a ₁₂=−0.282923×10⁻⁸

b ₁₂=−0.298726×10⁻⁹

f=70.704  (30)

When each parameter of the ocular lens is set as shown by the equations(30), shapes of the lenses 311, 312, 321, and 322 are as shown in FIG.98. Further, when the pupil exists on the optical axis, an optical pathdiagram as shown in FIG. 98 is drawn. A spherical aberration, anastigmatism, and a distortion aberration in this case are as shown inFIG. 99 and lateral aberrations on the image surface are as shown inFIG. 100.

FIG. 101 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (30).Further, FIG. 102 shows lateral aberrations on the image surface in thiscase.

Subsequently, in the case where only the surface 312B on the screen sideof the lens 312 in the first lens group 301 is formed by the asphericalsurface and the coefficient k₁₂ is set to 1.2 as an upper limit valuewithin the range shown in the relational expression (28), each parameterof the ocular lens is, for instance, as shown below.

r0=∞d0=40.000000

r1=45.35307 d1=24.984328 nd1=1.511234 υd1=64.2827

r2=−46.28172 d2=3.000000 nd2=1.487000 υd2=70.4000

r3=−86.15767 d3=4.572285

r4=−128.71885 d4=3.000000 nd4=1.747277 υd4=37.6752

r5=43.40071 d5=24.443387 nd5=1.487000 υd5=70.4000

r6=−43.83295 d6=40.000007

r7=−75.00000

a ₁₂=0.488893×10⁻⁵

b ₁₂=0.401212×10⁻⁹

f=70.704  (31)

When each parameter of the ocular lens is set as shown by the equations(31), shapes of the lenses 311, 312, 321, and 322 are as shown in FIG.103. Further, when the pupil exists on the optical axis, an optical pathdiagram as shown in FIG. 103 is drawn. A spherical aberration, anastigmatism, and a distortion aberration in this case are as shown inFIG. 104 and lateral aberrations on the image surface are as shown inFIG. 105.

FIG. 106 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (31).Further, FIG. 107 shows lateral aberrations on the image surface in thiscase.

FIG. 108 shows a constructional example of the seventh embodiment of anocular lens which is used as lenses 13L and 13R constructing theenlargement optical system. In the diagram, portions corresponding tothose in case of FIG. 78 are designated by the same reference numerals.That is, the ocular lens is fundamentally constructed in a mannersimilar to the case of FIG. 78.

In the seventh embodiment, in the first lens group 301 or second lensgroup 302, only a surface 321A on the pupil side of the lens 321constructing the second lens group 302 is formed by an asphericalsurface. In this case, further, now assuming that a quartic asphericalcoefficient of the surface 321A on the pupil side of the second lensgroup 302 is labeled as a₂₁ and the focal distance of the whole systemof the ocular lens is set to f and a predetermined coefficient is set tok₂₁, respectively, the coefficient k₂₁ is set so as to satisfy thefollowing relational expression.

−1.0<k ₂<−0.5 where, a ₂₁=(k ₂₁ /f)³  (32)

This is because if the coefficient k₂₁ is equal to −1.0 or less, theimage surface in the peripheral region of the picture plane of the videoimage is excessively bent in the negative direction and the resolutiondeteriorates. On the other hand, this is also because if the coefficientk₂₁ is equal to −0.5 or more, when the pupil moves from the opticalaxis, the image surface in the peripheral portion of the picture planeof the video image on the side opposite to the moving direction fallsdown in the positive direction and the resolution deteriorates.

Subsequently, in the case where only the surface 321A on the pupil sideof the lens 321 in the second lens group 302 is formed by the asphericalsurface and the coefficient k₂₁ is set to −0.8 as a value within theintermediate range of the range shown in the relational expression (32),each parameter of the ocular lens is, for instance, as shown below.

r0=∞d0=40.000000

r1=51.53362 d1=25.734500 nd1=1.637960 υd1=56.9431

r2=−138.26306 d2=3.000000 nd2=1.755000 υd2=27.6000

r3=177.92592 d3=2.134425

r4=92.12853 d4=8.878594 nd4=1.744000 υd4=44.7000

r5=38.73840 d5=18.683144 nd5=1.501478 υd5=68.8479

r6=−72.62546 d6=40.000000

r7=−75.00000

a ₂₁=−0.144856×10⁻⁵

b ₂₁=−0.456271×10⁻⁹

f=70.704  (33)

where, b₂₁ denotes a sextic aspherical coefficient of the surface 321Aon the pupil side of the lens 321 of the second lens group 302 as anaspherical surface.

When each parameter of the ocular lens is set as shown by the equations(33), shapes of the lenses 311, 312, 321, and 322 are as shown in FIG.108. Further, when the pupil exists on the optical axis, an optical pathdiagram as shown in FIG. 108 is drawn. A spherical aberration, anastigmatism, and a distortion aberration in this case are as shown inFIG. 109 and lateral aberrations on the image surface are as shown inFIG. 110.

FIG. 111 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (33).Further, FIG. 112 shows lateral aberrations on the image surface in thiscase.

Subsequently, in the case where only the surface 321A on the pupil sideof the lens 321 in the second lens group 302 is formed by the asphericalsurface and the coefficient k₂₁ is set to −1.0 as a lower limit valuewithin the range shown in the relational expression (32), each parameterof the ocular lens is, for instance, as shown below.

r0=∞d0=40.000000

r1=50.93361 d1=30.810164 nd1=1.638947 υd1=56.7747

r2=−80.61686 d2=3.000000 nd2=1.755000 υd2=27.6000

r3=130.33798 d3=4.739208

r4=116.91932 d4=3.000000 nd4=1.501781 υd4=68.8172

r5=48.67346 d5=18.379810 nd5=1.487000 υd5=70.4000

r6=−66.31831 d6=40.074024

r7=−75.00000

a ₂₁=−0.282896×10⁻⁵

b ₂₁=−0.135659×10⁻⁸

f=70.708  (34)

When each parameter of the ocular lens is set as shown by the equations(34), shapes of the lenses 311, 312, 321, and 322 are as shown in FIG.113. Further, when the pupil exists on the optical axis, an optical pathdiagram as shown in FIG. 113 is drawn. A spherical aberration, anastigmatism, and a distortion aberration in this case are as shown inFIG. 114 and lateral aberrations on the image surface are as shown inFIG. 115.

FIG. 116 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (34).Further, FIG. 117 shows lateral aberrations on the image surface in thiscase.

Subsequently, in the case where only the surface 321A on the pupil sideof the lens 321 in the second lens group 302 is formed by the asphericalsurface and the coefficient k₂₁ is set to −0.5 as an upper limit valuewithin the range shown in the relational expression (32), each parameterof the ocular lens is, for instance, as shown below.

r0=∞d0=40.000000

r1=54.25936 d1=20.371520 nd1=1.593045 υd1=61.7750

r2=−49.98184 d2=18.762553 nd2=1.744000 υd2=44.7000

r3=−153.31734 d3=1.000000

r4=72.07611 d4=3.000000 nd4=1.748554 υd4=35.5128

r5=31.41941 d5=16.865927 nd5=1.487000 υd5=70.4000

r6=−1306.83799 d6=40.000000

r7=−75.00000

a ₂₁=−0.353654×10⁻⁶

b ₂₁=−0.296813×10⁻⁹

f=70.704  (35)

When each parameter of the ocular lens is set as shown by the equations(35), shapes of the lenses 311, 312, 321, and 322 are as shown in FIG.118. Further, when the pupil exists on the optical axis, an optical pathdiagram as shown in FIG. 118 is drawn. A spherical aberration, anastigmatism, and a distortion aberration in this case are as shown inFIG. 119 and lateral aberrations on the image surface are as shown inFIG. 120.

FIG. 121 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (35).Further, FIG. 122 shows lateral aberrations on the image surface in thiscase.

FIG. 123 shows a constructional example of the eighth embodiment of anocular lens which is used as lenses 13L and 13R constructing theenlargement optical system. In the diagram, portions corresponding tothose in case of FIG. 78 are designated by the same reference numerals.That is, the ocular lens is fundamentally constructed in a mannersimilar to the case of FIG. 78.

In the eighth embodiment, in the first lens group 301 or second lensgroup 302, only a surface 322B on the screen side of the lens 322constructing the second lens group 302 is formed by an asphericalsurface. In this case, further, now assuming that a quartic asphericalcoefficient of the surface 322B on the screen side of the second lensgroup 302 is labeled as a₂₂ and the focal distance of the whole systemof the ocular lens is set to f and a predetermined coefficient is set tok₂₂, respectively, the coefficient k₂₂ is set so as to satisfy thefollowing relational expression.

−0.2<k ₂₂<1.4 where, a ₂₂=(k ₂₂ /f)  (36)

This is because if the coefficient k₂₂ is equal to −0.2 or less, theimage surface in the peripheral region of the picture plane of the videoimage on the side opposite to the moving direction falls down in thepositive direction and the resolution deteriorates. On the other hand,this is also because if the coefficient k₂₂ is equal to 1.4 or more, theimage surface in the intermediate region (hatched portion in FIG. 23)between the center portion and the peripheral portion of the pictureplane of the video image is excessively bent in the positive direction,the image surface in the peripheral portion is excessively bent in thenegative direction, and the resolution deteriorates.

Subsequently, in the case where only the surface 322B on the screen sideof the lens 322 in the second lens group 302 is formed by the asphericalsurface and the coefficient k₂₂ is set to 1.0 as a value within theintermediate range of the range shown in the relational expression (36),each parameter of the ocular lens is, for instance, as shown below.

r0=∞d0=40.000000

r1=53.25800 d1=24.594861 nd1=1.489267 υd1=69.0034

r2=−95.29804 d2=3.000000 nd2=1.751184 υd2=31.7766

r3=470.65448 d3=1.905110

r4=51.15860 d4=10.173024 nd4=1.744000 υd4=44.7000

r5=31.00215 d5=20.327005 nd5=1.487000 υd5=70.4000

r6=−105.92664 d6=40.000000

r7=−75.00000

a ₂₂=0.282923×10⁻⁵

b ₂₂=0.263858×10⁻¹¹

f=70.704  (37)

where, b₂₂ denotes a sextic aspherical coefficient of the surface 322Bon the screen side of the lens 322 of the second lens group 302 as anaspherical surface.

When each parameter of the ocular lens is set as shown by the equations(37), shapes of the lenses 311, 312, 321, and 322 are as shown in FIG.123. Further, when the pupil exists on the optical axis, an optical pathdiagram as shown in FIG. 123 is drawn. A spherical aberration, anastigmatism, and a distortion aberration in this case are as shown inFIG. 124 and lateral aberrations on the image surface are as shown inFIG. 125.

FIG. 126 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (37).Further, FIG. 127 shows lateral aberrations on the image surface in thiscase.

Subsequently, in the case where only the surface 322B on the screen sideof the lens 322 in the second lens group 302 is formed by the asphericalsurface and the coefficient k₂₂ is set to −0.2 as a lower limit valuewithin the range shown in the relational expression (36), each parameterof the ocular lens is, for instance, as shown below.

r0=∞d0=40.000000

r1=54.45186 d1=20.611380 nd1=1.587757 υd1=62.0893

r2=−48.72213 d2=20.140800 nd2=1.744913 υd2=42.4859

r3=−142.45322 d3=1.000000

r4=62.92736 d4=3.000000 nd4=1.749529 υd4=34.0261

r5=30.83249 d5=15.247820 nd4=1.487000 υd4=70.4000

r6=357.62396 d6=40.000000

r7=−75.00000

a ₂₂=−0.226338×10⁻⁷

b ₂₂=0.223811×10⁻⁸

f=70.704  (38)

When each parameter of the ocular lens is set as shown by the equations(38), shapes of the lenses 311, 312, 321, and 322 are as shown in FIG.128. Further, when the pupil exists on the optical axis, an optical pathdiagram as shown in FIG. 128 is drawn. A spherical aberration, anastigmatism, and a distortion aberration in this case are as shown inFIG. 129 and lateral aberrations on the image surface are as shown inFIG. 130.

FIG. 131 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (38).Further, FIG. 132 shows lateral aberrations on the image surface in thiscase.

Subsequently, in the case where only the surface 322B on the screen sideof the lens 322 in the second lens group 302 is formed by the asphericalsurface and the coefficient k₂₂ is set to 1.4 as an upper limit valuewithin the range shown in the relational expression (36), each parameterof the ocular lens is, for instance, as shown below.

r0=∞d0=40.000000

r1=40.50842 d1=20.778826 nd1=1.512048 υd1=58.0043

r2=−147.28690 d2=3.000000 nd2=1.749294 υd2=34.3723

r3=78.38449 d3=1.000000

r4=34.45382 d4=3.000000 nd4=1.737236 υd4=45.2369

r5=24.59147 d5=23.037221 nd5=1.487000 υd5=70.4000

r6=−238.11515 d6=40.000000

r7=−75.00000

a ₂₂=0.776340×10⁻⁵

b ₂₂=0.332592×10⁻⁸

f=70.704  (39)

When each parameter of the ocular lens is set as shown by the equations(39), shapes of the lenses 311, 312, 321, and 322 are as shown in FIG.133. Further, when the pupil exists on the optical axis, an optical pathdiagram as shown in FIG. 133 is drawn. A spherical aberration, anastigmatism, and a distortion aberration in this case are as shown inFIG. 134 and lateral aberrations on the image surface are as shown inFIG. 135.

FIG. 136 shows an optical path diagram which is drawn when the pupil isdeviated from the optical axis by only 9 mm in the case where eachparameter of the ocular lens is set as shown in the equations (39).Further, FIG. 137 shows lateral aberrations on the image surface in thiscase.

According to the construction as described above, high resolution isobtained over angles of view of 40° or more as a diagonal angle, and theocular lens which has high resolution can be provided even if the pupilposition is slightly deviated from the optical axis. The eye relief andback focus with a good balance and a long distance can be assured.

As will be obviously understood from the equations (25) to (27), (29) to(31), (33) to (35), and (37) to (39), both of the eye relief d0 and theback focus d6 are equal to or larger than 0.56f and they are wellbalanced and a long distance is assured.

The display apparatus 7 for forming a virtual image of a video image bythe ocular lens and providing as described above will now be described.

FIG. 138 shows a 20th constructional example of the display apparatus 7.

A display element (image display element) 331 is, for example, a displaydevice of the self light emitting type or transmitting type constructedin a manner similar to the display element 151 in FIG. 67 and displays avideo image to be provided for the user. The video image displayed inthe display element 331 enters a half mirror 334 through a projectinglens 332. In the half mirror 334, the light from the projecting lens 332is reflected by 90° and is irradiated to a reflecting type screen 333.The reflecting type screen 333 is a screen having a curved surface suchthat it coincides with an image surface of an ocular lens 335 and itreflects the light from the half mirror 334 by 180°. The reflected lighttransmits the half mirror 334 and passes through the ocular lens 335constructed as shown in FIGS. 78, 93, 123, or the like, so that itenters the eyeballs of the user. Thus, a virtual image of the videoimage displayed in the display element 331 is observed by the eyeballsof the user.

FIG. 139 shows a 21st constructional example of the display apparatus 7.In the diagram, portions corresponding to those in case of FIG. 138 aredesignated by the same reference numerals. That is, this video imageproviding apparatus is constructed in a manner similar to the case ofFIG. 138 except that the half mirror 334 is arranged between theprojecting lens 332 and reflecting type screen 333 instead of a positionbetween the reflecting type screen 333 and ocular lens 335.

In FIG. 139, the video image displayed in the display element 331 isirradiated to the reflecting type screen 333 through the projecting lens332 and half mirror 334. In the reflecting type screen 333, light fromthe half mirror 334 is reflected by 180°. The reflected light is furtherreflected by 90° in the half mirror 334 and enters the ocular lens 335.In a manner similar to the case of FIG. 138, a virtual image of thevideo image displayed in the display element 331 is observed by theeyeballs of the user.

FIG. 140 shows a 22nd constructional example of the display apparatus 7.In the diagram, portions corresponding to those in case of FIG. 138 aredesignated by the same reference numerals. That is, this displayapparatus 7 is constructed in a manner similar to the case of FIG. 138except that a display element 351 and a PBS 352 are provided in place ofthe display element 331.

Light as illumination light emitted from a light source (not shown) isreflected by 90° in the PBS 352 and enters the display element (imagedisplay element) 351. The display element 351 is, for example, areflecting type display device which is constructed in a manner similarto the display element 171 in FIG. 70. The light entering there isreflected, thereby displaying a video image to be provided for the user.

The video image as reflection light reflected by the display element 171transmits the PBS 352 and enters the projecting lens 332. In a mannersimilar to the case of FIG. 138, a virtual image is observed by theeyeballs of the user.

A half mirror and another element for dividing the light can be alsoprovided in place of the PBS 352.

FIG. 141 shows a 23rd constructional example of the display apparatus 7.In the diagram, portions corresponding to those in case of FIG. 140 aredesignated by the same reference numerals. That is, this video imageproviding apparatus is constructed in a manner similar to the case ofFIG. 140 except that the PBS 352 is arranged between the projecting lens332 and half mirror 334 instead of a position between the displayelement 351 and projecting lens 332.

In this case, light as illumination light emitted from a light source(not shown) is reflected by 90° in the PBS 352 and enters the displayelement 351 through the projecting lens 332. In the display element 351,the light entering there is reflected, the video image as a reflectionlight transmits the projecting lens 333332 and PBS 352, and enters thehalf mirror 334. In a manner similar to the case of FIG. 140, a virtualimage is observed by the eyeballs of the user.

FIG. 142 shows a 24th constructional example of the display apparatus 7.

In light emitting diodes 391R, 391G, and 391B, light of red, green, andblue is emitted as illumination light, respectively. The light enters aPBS 395 through a dichroic prism 392, a fly eye lens 393, and a fieldlens 394, respectively. In the PBS 395, the light from the field lens394 is reflected by 90° and its reflected light enters a reflecting typevideo display panel 396 as a reflecting type display element. In thereflecting type video display panel 396, by reflecting the lightentering there, a video image to be provided to the user is formed. Thereflected light as a video image enters a half mirror 400 through thePBS 395 and a projecting lens 397. In the half mirror 400, the videoimage from the projecting lens 397 is reflected by 90°, so that thevideo image is enlarged and projected to a reflecting type screen 398.The enlarged and projected image enters the eyeballs of the user throughan ocular lens 399 constructed as shown in FIGS. 78, 93, 108, 123, orthe like. Thus, a virtual image of the video image displayed on thereflecting type video display panel 396 is observed by the eyeballs ofthe user.

In this case, since the light of red, green, and blue is irradiated asillumination light to the reflecting type display panel 396, a colorvirtual image can be provided by what is called a field sequentialsystem.

FIG. 143 shows a 25th constructional example of the display apparatus 7.In the diagram, portions corresponding to those in the case of FIG. 142are designated by the same reference numerals. That is, this video imageproviding apparatus is constructed in a manner similar to the case ofFIG. 142 except that a mirror 401 is provided between the fly eye lens393 and field lens 394.

In the embodiment, light as illumination light from the fly eye lens 393is reflected by 90° by the mirror 401 and enters the PBS 395 through thefield lens 394. In the PBS 395, the light from the field lens 394 isreflected by 90° and the reflected light enters the reflecting typevideo display panel 396. In the reflecting type video display panel 396,the light entering there is reflected, thereby forming a video image tobe provided to the user. The reflected light as a video image enters thehalf mirror 400 through the PBS 395 and projecting lens 397. In the halfmirror 400, the light from the projecting lens 397 is reflected by 90°and the reflected light is projected to the reflecting type screen 398.In a manner similar to the case of FIG. 142, a virtual image of thevideo image displayed on the reflecting video display panel 396 isobserved by the eyeballs of the user.

In this case, since the optical path is bent by the mirror 401, theapparatus can be miniaturized.

FIG. 144 shows a 26th constructional example of the display apparatus 7.

In the embodiment, two sets of video image providing apparatuses shownin FIG. 143 are provided, thereby enabling virtual images which areformed to be observed by the right and left eyes, respectively.

That is, in FIG. 144, light emitting diodes 391RL, 391GL, and 391BL, adichroic prism 392L, a fly eye lens 393L, a field lens 394L, a PBS 395L,a reflecting type video display panel 396L, a projecting lens 397L, areflecting type screen 398L, an ocular lens 399L, a half mirror 400L,and a mirror 401L are constructed in a manner similar to the lightemitting diodes 391R, 391G, and 391B, dichroic prism 392, fly eye lens393, field lens 394, PBS 395, reflecting type video display panel 396,projecting lens 397, reflecting type screen 398, ocular lens 399, halfmirror 400, and mirror 401 in FIG. 143, respectively, thereby enabling avirtual image to be provided to the left eye of the user. In FIG. 144,light emitting diodes 391RR, 391GR, and 391BR, a dichroic prism 392R, afly eye lens 393R, a field lens 394R, a PBS 395R, a reflecting typevideo display panel 396R, a projecting lens 397R, a reflecting typescreen 398R, an ocular lens 399R, a half mirror 400R, and a mirror 401Rare also constructed in a manner similar to the light emitting diodes391R, 391G, and 391B, dichroic prism 392, fly eye lens 393, field lens394, PBS 395, reflecting type video display panel 396, projecting lens397, reflecting type screen 398, ocular lens 399, half mirror 400, andmirror 401 in FIG. 143, respectively, thereby enabling a virtual imageto be provided to the right eye of the user.

In this case, therefore, the user can observe the virtual images by theright and left eyes.

The arranging positions of the mirror 401 in FIG. 143 and the mirrors401L and 401R in FIG. 144 are not limited to the positions shown inFIGS. 143 and 144. That is, in the embodiment of FIGS. 143 or 144, themirrors are arranged so as to bend the optical path in the directionwhich is parallel with the drawing. However, as another arrangement, forexample, the mirrors can be also arranged so as to bend the optical pathin the direction perpendicular to the drawing.

The ocular lens shown in FIGS. 78, 93, 108, 123, or the like can be alsoused, for example, in case of observing a virtual image of the aerialimage 161 as shown in FIG. 68. In this case, for example, it isdesirable to form the aerial image 161 in a curved shape like thereflecting type screen 333 shown in FIG. 138.

The ocular lens shown in FIGS. 78, 93, 108, 123, or the like can be alsoused, for example, as an ocular lens 199 (199L, 199R) or the like shownin FIGS. 75 to 77 or the like. That is, the ocular lens shown in FIGS.78, 93, 108, 123, or the like can be also used in case of observing avirtual image of an image (video image) formed without using thereflecting type screen.

As mentioned above, according to the display apparatus 7 using theocular lens constructed as shown in FIGS. 78, 93, 108, 123, or the likeas an ocular lens, a video image of high resolution and a wide angle ofview can be provided. Further, even if the pupil of the user is out ofthe optical axis, a video image (virtual image) of high resolution canbe provided. Besides, the eye relief and back focus can be assured witha good balance. Therefore, it is possible to cope with a case where theuser moves in the optical axial direction and the screen and the ocularlens can be arranged at separate positions. Since the number of lensesconstructing the ocular lens is small, the miniaturization and lightweight of the apparatus can be realized.

In the foregoing case, in the first lens group 301 or second lens group302, only any one of the surfaces is formed by the aspherical surface.However, two or more surfaces can be also formed by aspherical surfaces.

Further, as for the ocular lens shown in FIGS. 78, 93, 108, 123, or thelike, the quartic aspherical coefficient of the lens has been limited.In those ocular lenses as well, however, for instance, by limiting thesextic aspherical coefficient of the lens, performance similar to thatin case of limiting the quartic aspherical coefficient of the lens canbe obtained.

According to the display apparatus disclosed in claim 1, since the videoimage providing apparatus is fixed to a predetermined object other thanthe user by the fixing means, the user can appreciate a virtual imagewith presence without, for example, attaching it.

According to the display apparatus disclosed in claim 42, among aplurality of lenses constructing the enlargement optical system, thelens arranged at the position that is the closest to the display meanshas a refractive power larger than those of the other lenses, while thelens arranged at the position that is the farthest from the displaymeans has a refractive power smaller than those of the other lenses.Therefore, even if the position of the eyeballs of the user is slightlymoved, a clear virtual image can be observed.

What is claimed is:
 1. A display apparatus having a video imageproviding apparatus for providing a video image to a user, said videoimage providing apparatus comprising: display means for displaying thevideo image; an enlargement optical system for forming a virtual imageby enlarging the video image displayed on said display means and forarranging, at a position in a space, a right eye image presented to theright eye of the user and a left eye image presented to the left eye ofthe user, said enlargement optical system including a left eye opticalsystem for the left eye and a right eye optical system for the right eyewhich have different optical axes, said enlargement system furtherincluding a concave surface mirror; and fixing means for fixing saidvideo image providing apparatus to a predetermined object other than theuser, wherein each of said left eye optical system and said right eyeoptical system includes at least one lens for enlarging the video image.2. A display apparatus according to claim 1, characterized in that saidvideo image providing apparatus provides a 2-dimensional virtual image.3. A display apparatus according to claim 1, characterized in that saidvideo image providing apparatus has left eye display means for the lefteye and right eye display means for the right eye as said display meansand allows the left eye display means and the right eye display means todisplay a left eye video image for the left eye and a right eye videoimage for the right eye, thereby providing a stereoscopic virtual image.4. A display apparatus according to claim 1, characterized in that saiddisplay means including a self light emitting device for displaying thevideo image by light emitting elements for emitting light on a pixelunit basis.
 5. A display apparatus according to claim 1, characterizedin that said display means including a transmitting light control devicefor displaying the video image by controlling transmission of light. 6.A display apparatus according to claim 1, characterized in that saiddisplay means including a reflecting light control device for displayingthe video image by controlling reflection of light.
 7. A displayapparatus according to claim 1, characterized in that entry of externallight is allowed into said video image providing apparatus.
 8. A displayapparatus according to claim 1, characterized in that the left eyeoptical system and the right eye optical system have optical axesdifferent than an enlargement optical axis.
 9. A display apparatusaccording to claim 8, characterized in that said video image providingapparatus further has incident means for individually inputting saidvideo image which is displayed by said display means into said left eyeoptical system and said right eye optical system.
 10. A displayapparatus according to claim 1, characterized in that the distancebetween the lens adjacent the left eye and the lens adjacent the righteye is equal to about 2 to 8 mm.
 11. A display apparatus according toclaim 1, characterized in that said video image providing apparatusfurther has curving means for curving a surface on which the virtualimage that is formed by said enlargement optical system is arranged. 12.A display apparatus according to claim 1, characterized in that saidfixing means can move said video image providing apparatus to apredetermined position.
 13. A display apparatus according to claim 1,characterized in that said video image providing apparatus provides avideo image in which a horizontal angle of visibility is equal to orlarger than 15°.
 14. A display apparatus according to claim 1,characterized in that said enlargement optical system projects the videoimage displayed on said display means onto a reflecting screen to form aprojected virtual image.
 15. A display apparatus according to claim 1,characterized in that said enlargement optical system projects the videoimage displayed on said display means onto a translucent screen to forma projected virtual image.
 16. A display apparatus according to claim 1,characterized in that said enlargement optical system forms a virtualimage of an aerial image of the video image displayed on said displaymeans.
 17. A display apparatus according to claim 1, characterized inthat said apparatus further has user holding means for holding the user,and said fixing means fixes said video image providing apparatus to saiduser holding means.
 18. A display apparatus according to claim 17,characterized in that said user holding means can change a user holdingstate.
 19. A display apparatus according to claim 17, characterized inthat said user holding means vibrates in correspondence to an acousticsignal.
 20. A display apparatus according to claim 17, characterized inthat said user holding means holds the user in a sitting state.
 21. Adisplay apparatus according to claim 17, characterized in that saidenlargement optical system is constructed in a manner such that at leastin a range where a head portion of the user held in said user holdingmeans is movable, the virtual image is observable in its entirety.
 22. Adisplay apparatus according to claim 17, characterized in that saidfixing means is constructed so as to cover a head portion of the user ina state where the user is held in said user holding means and said videoimage providing apparatus is fixed in said fixing means.
 23. A displayapparatus according to claim 22, characterized in that said fixing meansincluding a device in which a transmittance of light is variable.
 24. Adisplay apparatus according to claim 17, characterized in that said userholding means holds the user so that an interval between a head portionof the user and said video image providing apparatus lies within 45 cm.25. A display apparatus having a video image providing apparatus forproviding a video image to a user, said video image providing apparatuscomprising: display means for displaying the video image, said displaymeans including a backlight that emits light onto the rear of atransmitting light control device, said transmitting light controldevice, having pixels formed therein, displaying the video image on thefront of the transmitting light control device by controlling thepixels; an enlargement optical system for forming a virtual image byenlarging the video image displayed on said display means and forarranging at a position in a space, a right eye image presented to theright eye of the user and a left eye image presented to the left eye ofthe user, said enlargement optical system including a concave surfacemirror, and fixing means for fixing said video image providing apparatusto a predetermined object other than the user.
 26. A display apparatushaving a video image providing apparatus for providing a video image toa user, said video image providing apparatus comprising: display meansfor displaying the video image, said display means including areflecting light control device for displaying the video image, saidreflecting light control device having elements corresponding to pixels,reflection of light from each of said elements being controlled incorrespondence to a video signal; an enlargement optical system forforming a virtual image by enlarging the video image displayed on saiddisplay means and for arranging at a position in a space, a right eyeimage presented to the right eye of the user and a left eye imagepresented to the left eye of the user and fixing means for fixing saidvideo image providing apparatus to a predetermined object other than theuser.
 27. A display apparatus having a video image providing apparatusfor providing a video image to a user, said video image providingapparatus comprising: display means for displaying the video image; anenlargement optical system for forming a virtual image by enlarging thevideo image displayed on said display means and for arranging at aposition in a space, a right eye image presented to the right eye of theuser and a left eye image presented to the left eye of the user, andfixing means for fixing said video image providing apparatus to apredetermined object other than the user, wherein said video imageproviding apparatus includes a shutter apparatus allowing entry ofexternal light into said video image providing apparatus.
 28. A displayapparatus having a video image providing apparatus for providing a videoimage to a user, said video image providing apparatus comprising:display means for displaying the video image; an enlargement opticalsystem for forming a virtual image by enlarging the video imagedisplayed on said display means and for arranging at a position in aspace, a right eye image presented to the right eye of the user and aleft eye image presented to the left eye of the user, said enlargementoptical system being an optical system of one optical axis and includinga concave surface mirror, and fixing means for fixing said video imageproviding apparatus to a predetermined object other than the user.
 29. Adisplay apparatus having a video image providing apparatus for providinga video image to a user, said video image providing apparatuscomprising: a display means for displaying the video image; anenlargement optical system for forming a virtual image by enlarging thevideo image displayed on said display means and for arranging saidvirtual image at a position in a space, said enlargement optical systemincluding an optical system for the left eye and an optical system forthe right eye and further including a concave surface mirror; incidentmeans for individually inputting said video image which is displayed bysaid display means into said optical system for the left eye and saidoptical system for the right eye, and fixing means for fixing said videoimage providing apparatus to a predetermined object other than the user.30. A display apparatus having a video image providing apparatus forproviding a video image to a user, said video image providing apparatuscomprising: display means for displaying the video image; an enlargementoptical system for forming a virtual image by enlarging the video imagedisplayed on said display means and for arranging at a position in aspace, a right eye image presented to the right eye of the user and aleft eye image presented to the left eye of the user, said enlargementoptical system including a left eye optical system for the left eye anda right eye optical system for the right eye, and fixing means forfixing said video image providing apparatus to a predetermined objectother than the user, and wherein the distance between the lens adjacentthe left eye and the lens adjacent the right eye is equal to about 2 to8 mm.
 31. A display apparatus having a video image providing apparatusfor providing a video image to a user, said video image providingapparatus comprising: display means for displaying the video image; anenlargement optical system for forming a virtual image by enlarging thevideo image displayed on said display means and for arranging at aposition in a space, a right eye image presented to the right eye of theuser and a left eye image presented to the left eye of the user; curvingmeans for curving a surface on which the virtual image that is formed bysaid enlargement optical system is arranged, and fixing means for fixingsaid video image providing apparatus to a predetermined object otherthan the user.
 32. A display apparatus having a video image providingapparatus for providing a video image to a user, said video imageproviding apparatus comprising: display means for displaying the videoimage; an enlargement optical system for forming a virtual image byenlarging the video image displayed on said display means and forarranging said virtual images which are observed by the right and lefteyes of the user at a same position in a space; user holding means forholding the user wherein said user holding means vibrates incorrespondence to an acoustic signal; and fixing means for fixing saidvideo image providing apparatus to said user holding means.
 33. Adisplay apparatus according to claim 32, wherein said user holding meanscan change a user holding state.
 34. A display apparatus according toclaim 32, wherein said user holding means holds the user in a sittingstate.
 35. A display apparatus according to claim 32, wherein saidenlargement optical system is constructed in a manner such that at leastin a range where a head portion of the user held in said user holdingmeans is movable, the whole virtual image can be observed.
 36. A displayapparatus according to claim 32, wherein said user holding means holdsthe user so that an interval between a head portion of the user and saidvideo image providing apparatus lies within 45 cm.
 37. A displayapparatus according to claim 32, wherein said fixing means isconstructed so as to cover a head portion of the user in a state wherethe user is held in said user holding means and said video imageproviding apparatus is fixed in said fixing means.
 38. A displayapparatus according to claim 37, wherein said fixing means including adevice in which a transmittance of light is variable.
 39. A displayapparatus having a video image providing apparatus for providing a videoimage to a user, said video image providing apparatus comprising:display means for displaying the video image; an enlargement opticalsystem for forming a virtual image by enlarging the video imagedisplayed on said display means and for arranging at a position in aspace, a right eye image presented to the right eye of the user and aleft eye image presented to the left eye of the user; and means for (1)fixing said video image providing apparatus to a user holding means,wherein said user holding means vibrates in correspondence to anacoustic signal and (2) moving said video image providing apparatus to apredetermined position.
 40. A display apparatus having a video imageproviding apparatus for providing a video image to a user, said videoimage providing apparatus comprising: display means for displaying thevideo image; an enlargement optical system for forming a virtual imageby enlarging the video image displayed on said display means and forarranging at a position in a space, a right eye image presented to theright eye of the user and a left eye image presented to the left eye ofthe user; and fixing means for fixing said video image providingapparatus to a user holding means, wherein said video image providingapparatus provides a video image in which a horizontal angle ofvisibility is equal to or larger than 15°.
 41. A display apparatushaving a video image providing apparatus for providing a video image toa user, said video image providing apparatus comprising: display meansfor displaying the video image; an enlargement optical system forforming a virtual image by enlarging the video image displayed on saiddisplay means and for arranging at a position in a space, a right eyeimage presented to the right eye of the user and a left eye imagepresented to the left eye of the user; and fixing means for fixing saidvideo image providing apparatus to a user holding means, wherein abacklight that emits light onto the rear of a translucent light controlunit, said translucent light control unit, having pixels formed therein,displaying the video image on the front of the translucent light controldevice by controlling the pixels.
 42. A display apparatus having a videoimage providing apparatus for providing a video image to a user, saidvideo image providing apparatus comprising: display means for displayingthe video image; an enlargement optical system for forming a virtualimage by enlarging the video image displayed on said display means andfor arranging at a position in a space, a right eye image presented tothe right eye of the user and a left eye image presented to the left eyeof the user; and fixing means for fixing said video image providingapparatus to a user holding means, wherein said enlargement opticalsystem forms a virtual image of an aerial image of the video imagedisplayed on said display means.